View Full Version : FSB's in 2020?
In 2007 (https://www.m4carbine.net/showthread.php?6709-Fighting-AR-s-and-front-sights) most were in favor of (unshaved) front sight bases on serious guns, nearly unanimously in the case of unmagnified optics. (The thread then digressed into the value of pinning.) Browsing the photo threads today I see a lot of guns without a FSB. Do serious builds by the most knowledgeable still use FSB's?
Hell yes. An AR with no fixed FSB is not a serious fighting gun to me.
(don't get me wrong. I have lo pro blocks/FF rails and all that. They make great target guns and are good for long range stuff)
I wouldn’t put myself in the “most knowledgeable” category but I have fixed FSBs on every AR I currently have. I have a Sionics Patrol 3XL upper en route to me via UPS as we speak, and that has a free float handguard, because there is something specific I’m going to do with that upper that a free float works better for. In general though, I like fixed FSBs. I still shoot iron sights a lot too though, and probably because of that in most cases I feel better with a set of durable open sights that are a bit more substantial than simply rudimentary “back ups” to an optic.
I would think that is all personal preference and what the gun is going to be used for. Like a general patrol rifle with a red dot I see how in the quotes post that works, I have one rifle set up like that myself only my rear sight is fixed too. But with the use of magnified optics and or night vision equipment that’s space wasted on what may be a tertiary aiming device.
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PracticalRifleman
07-31-20, 08:54
There are many many tier 1 unite without FSBs. I don’t think they hurt, but a requirement? I’m not so sure.
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I am not most knowledgeable, but comments like markm’s have kept my go-to carbine with a FSB. In fact, it is a Kino, so the FSB’s only function is as a sight.
So I personally like a front site post of some sort, but all my barrels save 1, are free floated with a low profile gas block. I usually run a DD fixed front site post on my go to AR's because of that institutional Marine Corps knowledge that I can refer to it if I have an issue, but this was what I was taught in 2007. Having said that, I do have a beater gun with an Aimpoint Pro that still runs the old plastic magpul backups and I don't have an issue using that if I had to in a life or death situation. I look at my buddy who uses his for work and has magpul pro offsets folded down to allow for a dbal/ light and pressure pad, no FSB. I would refer to @Nowski87, it might just be personal preference.
We need some more manufacturers to make FSP cutout rails. DD and Centurion are all I’ve seen. You would think Geissele might make one.
We need some more manufacturers to make FSP cutout rails. DD and Centurion are all I’ve seen. You would think Geissele might make one.
PRI and Scalarworks makes them as well.
Slight thread hi-jack.
I'm converting two Colt 6920 rifles from DD 7.0 & 12.0 Omega rails to some type of M-LOK rails. Is there really a reason to have rail in front of the FSB? The additional real estate is nice, but I've never used it.
Thoughts?
I used to thing FSB we’re out dated, now? I find them superior and only build/trust guns with them.
You want your gas blocks pinned, FSBs have two.
Folding/add on non folders (mostly aluminum) sights break, dent, and or damage, FSB really don’t. They are strong as all hell.
Folder maybe outa sight, but really the FSB disappears too, when using a red dot. Your brain doesn’t focus on it. It essentially becomes invisible until you make a Conscious decision that you want to see it.
It’s always ready.
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titsonritz
07-31-20, 12:54
I have more guns with an FSB than I do without.
Five_Point_Five_Six
07-31-20, 12:58
I'm definitely not among the most knowledgeable, but I prefer a fixed FSB whenever possible. It's by far the most durable front sight option and it looks cool which is the most important thing. If you're using a quality red dot, the likelihood of it going down when you need it is slim, but if it does, the optic can be used as a ghost ring rear sight and you can do work with it and the front sight in a pinch, but you have to spend time on the range learning holds for that. Even on guns with free float rails and low pro gas blocks, I'm gonna run a fixed front sight like the Scalarworks.
Slight thread hi-jack.
I'm converting two Colt 6920 rifles from DD 7.0 & 12.0 Omega rails to some type of M-LOK rails. Is there really a reason to have rail in front of the FSB? The additional real estate is nice, but I've never used it.
Thoughts?
Light at the 12 o'clock position. I have a FSB cutout rail that accomplishes that and I have a Mossie Midnight Mount on another to accomplish the same 12 o'clock position.
Slight thread hi-jack.
I'm converting two Colt 6920 rifles from DD 7.0 & 12.0 Omega rails to some type of M-LOK rails. Is there really a reason to have rail in front of the FSB? The additional real estate is nice, but I've never used it.
Thoughts?
https://www.centurionarms.com/c4-mlok-rail-12in-fsp-p/081912p.htm
Centurion makes an Mlok rail that is probably close to what you are looking for.
What I wish is that manufacturers would use the round handguard retainer on basic midlength uppers. That way I could easily install the MOE SL handguard, which is friggin awesome for most purposes. I’m still trying to figure why they insist on the triangle retainer....
grizzlyblake
07-31-20, 15:05
To answer the OP, no. It appears many serious guns are now built with lo pro GBs and free float rails.
BangBang77
07-31-20, 15:31
PRI and Scalarworks makes them as well.
Hank
Can you provide a link to the Scalarworks FSB cutout rail? I am in the hunt for a cutout and haven't found one I like minus the RIS from DD and finding one is hit or miss and pricey...
ViniVidivici
07-31-20, 16:45
I agree the FSB will never go out of style or become irrelevant.
I always thought a MK18 FSP RIS II would be the perfect rail for 10.3-11.5 builds...
KAC doesn’t seem to think they are required.
There are many many tier 1 unite without FSBs. I don’t think they hurt, but a requirement? I’m not so sure.
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Yup. I prefer the extra handguard length on anything shorter than a M16. Although I dig Kinos and mock dissies.
What I wish is that manufacturers would use the round handguard retainer on basic midlength uppers. That way I could easily install the MOE SL handguard, which is friggin awesome for most purposes. I’m still trying to figure why they insist on the triangle retainer....
Yeah. Baffling.
PRI and Scalarworks makes them as well.
So does Midwest Industries
I always thought a MK18 FSP RIS II would be the perfect rail for 10.3-11.5 builds...
Who’s to say it’s not? https://uploads.tapatalk-cdn.com/20200731/517b48b0b190005aed076a7330ea5226.plist
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Who’s to say it’s not? https://uploads.tapatalk-cdn.com/20200731/517b48b0b190005aed076a7330ea5226.plist
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You're making me want to send an M4A1RIS II to chop boss...
The_War_Wagon
07-31-20, 19:43
This thread turned out a LOT differently than I thought it would!!!
I figured the FSB was as passe these days, as oval handguards! :blink:
dirkmagurk
07-31-20, 20:02
I prefer a FSB when using a red dot optic and a lo profile pinned gas block on my scoped rifles. I don’t understand why these otherwise high quality rifle assemblers continue to use set screws. The gas block is a critical component and gets extremely hot. I think most here would agree that using a thread locking compound to secure a castle nut is unacceptable. Then why has it become acceptable to use set screws and locking compound on gas blocks? I have a buddy that removes set screws from dimpled barreled gas blocks on a very highly regarded companies rifles by removing the handguard and firing a 30 round mag or two through it to heat it up enough to easily remove the set screws.
ColtSeavers
07-31-20, 20:49
What I wish is that manufacturers would use the round handguard retainer on basic midlength uppers.
This. It's 2020, why is there no option to choose which handguard cap you get?
I prefer a FSB when using a red dot optic and a lo profile pinned gas block on my scoped rifles. I don’t understand why these otherwise high quality rifle assemblers continue to use set screws. The gas block is a critical component and gets extremely hot. I think most here would agree that using a thread locking compound to secure a castle nut is unacceptable. Then why has it become acceptable to use set screws and locking compound on gas blocks? I have a buddy that removes set screws from dimpled barreled gas blocks on a very highly regarded companies rifles by removing the handguard and firing a 30 round mag or two through it to heat it up enough to easily remove the set screws.
And this. Again, it's 2020, why the hell are so few companies offering factory drilled barrels with gas blocks ready for pinning by end user? And why are clamp on gas blocks not more commonplace?
On topic: I only have FSBs on ARs that I have spefically built or configured to accomodate the FSB. Otherwise, I avoid them for more freedom.
Belmont31R
07-31-20, 21:07
I prefer a FSB when using a red dot optic and a lo profile pinned gas block on my scoped rifles. I don’t understand why these otherwise high quality rifle assemblers continue to use set screws. The gas block is a critical component and gets extremely hot. I think most here would agree that using a thread locking compound to secure a castle nut is unacceptable. Then why has it become acceptable to use set screws and locking compound on gas blocks? I have a buddy that removes set screws from dimpled barreled gas blocks on a very highly regarded companies rifles by removing the handguard and firing a 30 round mag or two through it to heat it up enough to easily remove the set screws.
Who the **** takes a customer's gun out to a range and fires a 30rd mag to do what a few seconds on a Home Depot MAPP torch can do? Then the range becomes the shop to work on guns?
If even the premise of that were true Internet forums would be filled with dudes with set screw gas blocks failing, and it would have been fixed over a decade ago when people were making equally nonsensical statements back then.
The actual cases of properly documented and installed set screw gas blocks failing are slim to almost none.
That said its not hard to pin a GB so why not?
Need it now? Pop it up. It's always pointed where the muzzle's pointed, not the rail.
https://www.ar15.com/media/mediaFiles/18978/Victor_sSPR_jpg-1521349.JPG
...why are clamp on gas blocks not more commonplace...?
Because the cross screws of a clamp on gas block are more likely to break than set screws are to back out. Especially if the set screws are staked.
ColtSeavers
08-01-20, 00:07
Because the cross screws of a clamp on gas block are more likely to break than set screws are to back out. Especially if the set screws are staked.
I've only been able to find two people that say they've had a clamp on cross screw break, and both happened during install or uninstall, not during live fire.
I've only been able to find two people that say they've had a clamp on cross screw break, and both happened during install or uninstall, not during live fire.
How many set screws have broken?
Cross screws bend and stretch as they're tightened, placing them under undue strain.
Set screws compress and the gas block is pulled tight against the gas port giving a better gas seal. Dimple the barrel, use a good set screw, stake them in place and they won't shoot loose.
A quality clamp on gas block isn't a horrible choice- in fact, a good clamp on gas block is a good choice. But taking in the details, a quality set screw gas block is better.
Need it now? Pop it up. It's always pointed where the muzzle's pointed, not the rail.
https://www.ar15.com/media/mediaFiles/18978/Victor_sSPR_jpg-1521349.JPG
Who makes that handguard?
And yes, I still prefer FSBs with red dots.
Revolution37
08-01-20, 02:51
My first AR was a 6920 (2011) with a FSB. I cut it down to put a 13.8” Troy Modular Rail Forend on it, because that was a good idea at the time. My next 3 ARs all had no FSB. I would not buy one with a FSB if I could avoid it.
https://www.centurionarms.com/c4-mlok-rail-12in-fsp-p/081912p.htm
Centurion makes an Mlok rail that is probably close to what you are looking for.
I just bought one of these after seeing pics in the C4 mlok thread not so long ago. I have a C4 quad rail on my Sionics rifle and love it, but this is even better IMHO.
You’ll be shocked by how light it is ...
dirkmagurk
08-01-20, 04:05
Who the **** takes a customer's gun out to a range and fires a 30rd mag to do what a few seconds on a Home Depot MAPP torch can do? Then the range becomes the shop to work on guns?
If even the premise of that were true Internet forums would be filled with dudes with set screw gas blocks failing, and it would have been fixed over a decade ago when people were making equally nonsensical statements back then.
The actual cases of properly documented and installed set screw gas blocks failing are slim to almost none.
That said its not hard to pin a GB so why not?
Customer? I think you misunderstood, they’re his personal rifles. When you own enough land in the right location you can do whatever the **** you want on it.
Most people don't shoot or practice with irons. Big army even stopped teaching irons. We have been in the age of optics for almost 3 decades. Some Tier one guys don't even run BUIS because they already have redundant aiming devices, or to save a few ounces, lack the rail space, they don't work with nods, etc.
As a gas block, the FSB is in no way superior to a LPGB. FSB are pinned because they are an exposed lever. A LPGB is completely protected under the handguard/rail and is not susceptible to any load bering force. A properly installed LPGB that incorporates a barrel dimple, the correct Loctite, and properly torqued set screws at 10-15" lbs is in no way inferior as a gas block than a pinned FSB.
Given that sights are seldom if ever used anymore by big army/marine corp, the main reason the FSB remains in the TDP is simply that bureaucratic/institutional inertia is difficult/impossible to overcome.
What are you talking about? Scalarworks does not make rails.
PRI and Scalarworks makes them as well.
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Straight Shooter
08-01-20, 07:18
Most people don't shoot or practice with irons. Big army even stopped teaching irons. We have been in the age of optics for almost 3 decades. Some Tier one guys don't even run BUIS because they already have redundant aiming devices, or to save a few ounces, lack the rail space, they don't work with nods, etc.
As a gas block, the FSB is in no way superior to a LPGB. FSB are pinned because they are an exposed lever. A LPGB is completely protected under the handguard/rail and is not susceptible to any load bering force. A properly installed LPGB that incorporates a barrel dimple, the correct Loctite, and properly torqued set screws at 10-15" lbs is in no way inferior as a gas block than a pinned FSB.
Given that sights are seldom if ever used anymore by big army/marine corp, the main reason the FSB remains in the TDP is simply that bureaucratic/institutional inertia is difficult/impossible to overcome.
Apparently the USMC doesnt teach irons anymore either- less than two years ago I was at the range when a new Marine fresh out of Parris Island came over after awhile- and asked me to teach him how to use irons. We had a nice hour or so course of instruction. He said all they taught him at that time was ACOGS. Really, really bothered me. I remember "snappin in week"...oh those sore muscles & "sling palsey".
If you're above average and diligent, there's a lot of conventional wisdom that isn't, and legacy that's adaptable. More skill = more options.
Haven't bought a gun with a fixed FSB in awhile, only long free float rails. My regular workhorses don't even have back up irons on them.
I see value in using the FSB inside the RDS as a close range back-up. When I had to teach that recently I installed one of these for the day, https://lmtdefense.com/product/l8fs/. No need to zero, but you need to know where you'll hit and limitations.
Spec'ing guns for the average and below, a fixed front, RDS, and a flip up iron is a good choice. Though, putting strugglers on guns with flip front and rears (or no irons) helps to keep them from combining sight systems. One struggling troop simply refused to ignore the fixed FSB in his dot window. When I took his gun away and gave him mine, he was apoplectic for awhile, but learned.
For gas blocks, in order of preference... 1) uni-directional taper pin (per spec), 2) set screw in a dimple, staked or high temp locker, 3) everything else. There's really no need to do anything other than 1 or 2.
Straight Shooter
08-01-20, 09:54
Whilst on the subject of Gas Blocks..has it been established..as far as ACCURACY goes..as to which method is better for precision shooting?
Whilst on the subject of Gas Blocks..has it been established..as far as ACCURACY goes..as to which method is better for precision shooting?
Criterion, as I recall, states that they believe the pin is detrimental to accuracy. I have yet to see anything objective. Their logic isn’t flawed, as far as I can tell, though.
Who makes that handguard?
And yes, I still prefer FSBs with red dots.
SLR made that one.
https://slrrifleworks.com/
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Diamondback
08-01-20, 10:54
For me it depends on the app... for magnification or optics-on-bench lo-pro it, if it's a "mid-range or less" Combat or CQB and there's a chance of seeing it get knocked around I want an FSB for durability. If it's bump-in-the-night or BOB and needs quick deployment, I want FSB for the reduced moving parts to deploy, especially if I have a sidefolder to deal with.
That said, I've been toying with an idea if I could find a manufacturer... an all-in-one light-laser-BUIS, something like an Insight M6X mounted upside-down on a top-rail with a sight post and wings on top of it, all three components stacked on the centerline.
EDIT: Of my three-and-a-half (the "half" is a mockup on an unmachined 80%), only one doesn't have an FSB, and of the next four under consideration (12.5" "GL/SSC-ish," M16A4 and C7A2, Holland) only one would be joining it.
MSG Jared Van Aalst (KIA, RIP) was one of my NCOs, formerly of the 3rd Ranger Battalion, the USAMU, the infantry sniper school, and Delta. He stated there was definitely a shift with the SPR's rail-mounted front sight if you leaned into the bipod for distance shots.
PracticalRifleman
08-01-20, 11:29
How many set screws have broken?
Cross screws bend and stretch as they're tightened, placing them under undue strain.
Set screws compress and the gas block is pulled tight against the gas port giving a better gas seal. Dimple the barrel, use a good set screw, stake them in place and they won't shoot loose.
A quality clamp on gas block isn't a horrible choice- in fact, a good clamp on gas block is a good choice. But taking in the details, a quality set screw gas block is better.
When I build a rifle, I drill dimples for the gas block set screws. Then I drill for a taper pin. Then I stake the gas block set screws. I’ve never had trouble with in coming loose and never had trouble getting one off.
I had a friend that had to grind off a popular brand’s gas block that was secured with a thread-locking compound because it wouldn’t budge with soaking in carbon remover, hammer taps, or Bob Smith’s Uncure. He eventually stripped both set screws and took the belt grinder to it.
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MontanaMarine
08-01-20, 16:35
I still prefer a FSB. I've got 13 uppers, and 11 have a FSB.
If the barrel shifts from strain or heat, the front sight is still in the same relation to the bore.
Plus it's pretty darn solid.
hotrodder636
08-01-20, 17:50
My next upper is likely to be a 6933.
I just bought one of these after seeing pics in the C4 mlok thread not so long ago. I have a C4 quad rail on my Sionics rifle and love it, but this is even better IMHO.
You’ll be shocked by how light it is ...
Feel good in the hands, not too bulky?
I will always put fsb's on kiss carbines. Even if the intended primary sighting is a red dot or EOTech.
But for something with a quality free float rail, lately I do not install FSBs. But do want/use pinned lo-pro blocks.
We need some more manufacturers to make FSP cutout rails. DD and Centurion are all I’ve seen. You would think Geissele might make one.
It's probably a supply and demand problem. There is not much demand, so there is little and only expensive supply.
Econ 101.
MSG Jared Van Aalst (KIA, RIP) was one of my NCOs, formerly of the 3rd Ranger Battalion, the USAMU, the infantry sniper school, and Delta. He stated there was definitely a shift with the SPR's rail-mounted front sight if you leaned into the bipod for distance shots.
I miss him greatly. One of the best NCO’s I’ve known. We are truly diminished by his loss. The rest of us are half-stepping in comparison.
My troops learn irons.
Most people don't shoot or practice with irons. Big army even stopped teaching irons. We have been in the age of optics for almost 3 decades. Some Tier one guys don't even run BUIS because they already have redundant aiming devices, or to save a few ounces, lack the rail space, they don't work with nods, etc.
Mt brother in law is still in the Army and he shoots irons regularly. Just texted my buddy who is an instructor at Benning and he says they are still taught
Mt brother in law is still in the Army and he shoots irons regularly. Just texted my buddy who is an instructor at Benning and he says they are still taught
Not for most of the army. The marksmanship course put on by Benning was still teaching irons last I heard but the majority of units I’m adware of don’t even zero them. Does your BIL just like irons?
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ColtSeavers
08-02-20, 16:06
Basic should be extended a week to 10 total, the extra week should be for BRM, and then teach both irons and optics, not simply forego one for the other (if that's what's happened since 2001).
Oh, and for the love of God, stop teachiing troops how to adjust for ranged targets, and then have them qualify on a 25m range, without telling them there's no adjustments to be made for the different simulated range sized targets. Cause that was a thing...
Basic should be extended a week to 10 total, the extra week should be for BRM, and then teach both irons and optics, not simply forego one for the other (if that's what's happened since 2001).
Oh, and for the love of God, stop teachiing troops how to adjust for ranged targets, and then have them qualify on a 25m range, without telling them there's no adjustments to be made for the different simulated range sized targets. Cause that was a thing...
Infantry OSUT at Ft. Benning is now 22 weeks long (which I personally think is a bit much). I'd wager they get schooled on irons somewhere in that menagerie.
That said, my FIL had a 2013 WWII reunion at Benning and I was told then that irons weren't used for qualifications (maybe a class?). I would sincerely hope that has changed in recent years, especially since they have all that extra time!
Most people don't shoot or practice with irons. Big army even stopped teaching irons. We have been in the age of optics for almost 3 decades. Some Tier one guys don't even run BUIS because they already have redundant aiming devices, or to save a few ounces, lack the rail space, they don't work with nods, etc.
As a gas block, the FSB is in no way superior to a LPGB. FSB are pinned because they are an exposed lever. A LPGB is completely protected under the handguard/rail and is not susceptible to any load bering force. A properly installed LPGB that incorporates a barrel dimple, the correct Loctite, and properly torqued set screws at 10-15" lbs is in no way inferior as a gas block than a pinned FSB.
Given that sights are seldom if ever used anymore by big army/marine corp, the main reason the FSB remains in the TDP is simply that bureaucratic/institutional inertia is difficult/impossible to overcome.
This. I agree 100%.
Infantry OSUT at Ft. Benning is now 22 weeks long (which I personally think is a bit much). I'd wager they get schooled on irons somewhere in that menagerie.
That said, my FIL had a 2013 WWII reunion at Benning and I was told then that irons weren't used for qualifications (maybe a class?). I would sincerely hope that has changed in recent years, especially since they have all that extra time!
My son finished Infantry OSUT at Ft Benning this year. They trained with irons but used the M68 for record qualification. My oldest son says they only used the ACOG in the Marines (Combat Engineer).
My HD AR has a red dot and FSB, as does my LMT SPM 14 "M4". My ARs with magnified optics run FF rails and no sights.
My 11.3 pistol is a hot mess - it has a fixed front sight mounted to a 10" free float rail over a pinned LPGB. It works though.
Andy
I have to admit I'm a bit surprised by the love for the FSB.
When I read discussions about 14.5 vs 16 inch barrels I see many wanting 14.5 to save a few ounces.
I figure eliminating the FSB would save some weight and allow the 16 inch barrel.
Diamondback
08-02-20, 20:39
My 11.3 pistol is a hot mess - it has a fixed front sight mounted to a 10" free float rail over a pinned LPGB. It works though.
But is it really a "hot mess" if it gets results where it counts?
ColtSeavers
08-02-20, 20:54
Infantry OSUT at Ft. Benning is now 22 weeks long (which I personally think is a bit much). I'd wager they get schooled on irons somewhere in that menagerie.
I'm specifically referring to Basic only, which every MOS goes through at every BCT post (Benign, Lost in the Woods, Relaxin Jackson, Ft. Shill, etc.)
But is it really a "hot mess" if it gets results where it counts?
It is a bit of an oddball, ALG Keymod rail; also has no forward assist or dust cover. But it's light, handy, and reliable. It has a longer sight radius than a carbine with FSB and it shoots pretty well.
Andy
also has no forward assist or dust cover.
Anderson upper receiver?
It's probably a supply and demand problem. There is not much demand, so there is little and only expensive supply.
Econ 101.
You would think there is a high demand. Seems like everything I look at is out of stock and people have no clue when it will be available, but I do agree with your post.
I like the FSB because I’m old fashioned. Also, I’m lazy and it’s one less part for me to have to order. That said, I think there are plenty of applications where iron sights aren’t really relevant. I am doing my best to put together parts for a slick pistol build where I don’t think irons make sense.
Five_Point_Five_Six
08-03-20, 10:18
I have to admit I'm a bit surprised by the love for the FSB.
When I read discussions about 14.5 vs 16 inch barrels I see many wanting 14.5 to save a few ounces.
I figure eliminating the FSB would save some weight and allow the 16 inch barrel.
Unless a person is actually carrying a rifle around everyday for a few hours or more, the importance of the whole "save a few ounces" thing is greatly overblown.
My 14.5 is a mid length government profile barrel with and FSB, it is not lite but it’s not overly heavy. But having B5 handgurads and stock helps.
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Anderson upper receiver?
I would guess it is. I bought it from MAS Defense quite a while ago. It fits perfectly and matches the finish on an Anderson lower.
Andy
ColtSeavers
08-03-20, 14:49
I would guess it is. I bought it from MAS Defense quite a while ago. It fits perfectly and matches the finish on an Anderson lower.
Andy
Could also be Mas Defense's own or Aero Precision. Incidentally, Mas defense was where I bought my wife's Aero slick side upper receiver years ago.
Most of mine have FSB’s, and if I were buying an AR tomorrow it would have an FSB as well. I’m just used to it at this point, and having one seems right to me. I also still run a BUIS in the up position (Daniel Defense A 1.5). Most here would probably say that’s an older way of doing things too.
vicious_cb
08-04-20, 02:14
An 8 page thread on what amounts to personal preference thats basically a backdoor necropost(OP just linked a dead and locked thread). I wish IG was still around.
LowSpeed_HighDrag
08-04-20, 05:14
FSB's are cool looking, much like the 1911 is. They serve the same purpose though: old guys can brag about owning something that tamed the frontier, stand when they pee, etc.
Slight thread hi-jack.
I'm converting two Colt 6920 rifles from DD 7.0 & 12.0 Omega rails to some type of M-LOK rails. Is there really a reason to have rail in front of the FSB? The additional real estate is nice, but I've never used it.
Thoughts?
My M4A1 SOCOM RISII FSP allows me to get a better forward clamp grip on it. It also allows a bit more space to mount my light on the other side without the lens being forward of the rail: which protects my expensive vampire.
I prefer the FSB for its rugged utility. I don’t believe they are required, but it’s critical to pin the gas block effectively, preferably two taper pins. My favorite gas block is still a shaved FSB, a Badger, and the Super Gas Block. PRI gas block looks solid also. Just have to mill the hole, taper ream it, and tap a pin or two into it. This is a measure twice, a jig is better process but I have installed a number successfully without a jig or mill.
Specops units seem to be going that way. Seems they need the rail space. If the lopro block us pinned I see no issue.
I would think that, in this day and age where carbines and rifles are sporting LPVOs or HPVOs with an offset electronic dot sight, a set of GOOD flip-up BUIS (Troy or KAC) would be better than any fixed front (and/or rear) sight - even if you had to place the front sight behind your laser/illuminator and white light. Stuff happens.
grizzlyblake
08-04-20, 20:26
I run Troys on my BCMs. My thought is that the factory installed gas block and gas tube are totally protected under the metal hand guard. They are not subject to any sort of impact at all. BCM doesn’t pin the gas blocks, and I guess you could shoot one loose (dimpled Barrel, two knurled screws with red loctite) but I’ve never heard of that happening.
I would not have an unpinned exposed FSB though if I had to have one.
call_me_ski
08-06-20, 13:54
My current serious use Ar15 still has a 7in KAC URX with a KAC flip up front sight gas block. I don’t think I would mind in the slightest if it just had a fix FSB instead. This thread reminded me that I have a KAC RIS II sitting a box unused. Might need to just grab a 10.3in FSB barrel and finally throw it together.
I've broken rails and rail mounted fixed front sights. They're massively more fragile than a real FSB. As far as weight savings, If I carry a carbine that many hours, all the more reason to have a solid sight that can stand up to punishment.
ColtSeavers
08-06-20, 20:53
I've broken rails and rail mounted fixed front sights. They're massively more fragile than a real FSB. As far as weight savings, If I carry a carbine that many hours, all the more reason to have a solid sight that can stand up to punishment.
Didn't you have one that flattened just falling onto your garage floor?
My new pistola build has an FSB. Its the most bombproof front sight out there. Think im gonna run a scalarworks rear on it.
Eurodriver
08-07-20, 07:43
MSG Jared Van Aalst (KIA, RIP) was one of my NCOs, formerly of the 3rd Ranger Battalion, the USAMU, the infantry sniper school, and Delta. He stated there was definitely a shift with the SPR's rail-mounted front sight if you leaned into the bipod for distance shots.
https://sofrep.com/news/lost-hero-msg-jared-van-aalst/
Everyone will remember him differently, his friends, family, team mates, and everyone else who crossed paths with him in one place or another. I remember him as an expert marksman who brought a sniper’s focus and attention to detail to every task he threw himself at. I remember the guy who had a sense of history and that I could talk about past Rangers and Ranger history with. I remember the dude who made knives and smoked cigars on the range. I also remember a perfectionist and a leader who held you to high standards.
:sad:
And then the EMP hit
And my Acogs and LPVO's continued to work as they always have.....
Hammer_Man
08-07-20, 11:09
For a hard use, WW3, Chinese invasion (WOLVERINES!!!), go to war gun, I choose a fixed FSB. I think a perfect setup would be a FSB on a mid length gun.
All my guns have either fsb or a pinned block under the rail,never have any issues that way,Js
justin_247
08-07-20, 11:44
For folks who are running an FSB and laser aiming devices, what kind of setup are you using?
I ask because when you're running an FSB, you give up several inches of top rail and the setup can feel a bit tight...
Hammer_Man
08-07-20, 14:53
For folks who are running an FSB and laser aiming devices, what kind of setup are you using?
I ask because when you're running an FSB, you give up several inches of top rail and the setup can feel a bit tight...
I run a KAC carbine RAS handguard, with a DBAL A3 and Surefire dual switch mounted at the 12 o’clock position. Space is tight, so I use a vertical grip to drive the weapon. I think my next build will use a mid length gas system and a 9” handguard.
Eurodriver
08-07-20, 16:35
For folks who are running an FSB and laser aiming devices, what kind of setup are you using?
I ask because when you're running an FSB, you give up several inches of top rail and the setup can feel a bit tight...
Centurion FSP rails.
Diamondback
08-07-20, 16:53
For folks who are running an FSB and laser aiming devices, what kind of setup are you using?
I ask because when you're running an FSB, you give up several inches of top rail and the setup can feel a bit tight...
For a "Mk 18-ish" with CASV, I slapped a Mossie Mount onto the front frame. Upside-down Lasermax on the Mossie, skinny MFT/Princeton light on top of the laser. It does help to note that there's a blast shield going around the FH to protect the electronics...
titsonritz
08-07-20, 17:00
Centurion FSP rails.
Yep, I also have DD M4A1 RIS II FSP
Diamondback
08-07-20, 17:02
There's also the old KAC MRE, but good luck finding one...
For a "Mk 18-ish" with CASV, I slapped a Mossie Mount onto the front frame. Upside-down Lasermax on the Mossie, skinny MFT/Princeton light on top of the laser. It does help to note that there's a blast shield going around the FH to protect the electronics...
I searched "Mossie Mount" to see what you were describing and I found this photo on the BCM website. Can the SureFire really take this? I note that you specifically mentioned a blast shield which I don't see here.
63346
Diamondback
08-07-20, 23:38
I searched "Mossie Mount" to see what you were describing and I found this photo on the BCM website. Can the SureFire really take this? I note that you specifically mentioned a blast shield which I don't see here.
63346
IraqGunz, may he Rest In Peace, actually used to rock a full-on DBAL on a Mossie occasionally. By blast shield I mean taking a collar like an Indian Creek BFD and mounting it around the FH...
https://images.squarespace-cdn.com/content/v1/56abf88001dbaea1a83c201e/1562702127493-AYE699V5WB5BAATQFPN4/ke17ZwdGBToddI8pDm48kJMYF2ucp936trTgPJ9mjVoUqsxRUqqbr1mOJYKfIPR7LoDQ9mXPOjoJoqy81S2I8N_N4V1vUb5AoIIIbLZhVYxCRW4BPu10St3TBAUQYVKcqA48JI6ZymLAIChs32D2kNosVVFvnZR1-qaflAsLMwCaMr-J36utqn4kgLKyo-Sl/BFD+BARREL+Assem1.JPG?format=1500w
Red is the collar, blue is the muzzle device, light gray is the barrel and dark gray is the collar mount.
https://www.indiancreekdesigninc.com/shop-online/bfd-with-12-mount-complete-except-thread-protector
Hammer_Man
08-08-20, 00:09
There's also the old KAC MRE, but good luck finding one...
Brownell’s and Operation Parts has them on the regular.
justin_247
08-08-20, 10:33
Centurion FSP rails.
Yep, I also have DD M4A1 RIS II FSP
This is the answer I was expecting. I haven't noticed very many folks mount their laser in front of the FSP, though, so it still seems kind of cramped. Plus you get the increased chance of burning yourself on the sight post.
It's also interesting that people seem to have one of two reasons for preferring the FSP to a rail mounted sight.
(1) Due to zero shift when shooting irons.
(2) For redundancy, with little concern for zero shift.
When looking at rail mounted aiming devices, the two don't seem reconcilable outside of using a Mossie mount or something similar that directly mounts the aiming device to the barrel assembly. Or you need to have a monolithic upper assembly that uses flip-up barrel-mounted irons, like the Colt 6940 or SCAR, at which point you're running out of hand space really quick and likely need to consider using a VFG.
justin_247
08-08-20, 10:46
The options that I see for folks who want to minimize zero shift with both fixed irons and an aiming device are the Mossie mount and Ergo forward rail:
https://cdn.shopify.com/s/files/1/0659/4513/products/Arisaka_Mossie_Mount_Low_Res_10_of_14_large.JPG?v=1507754016
https://palmettostatearmory.com/media/catalog/product/cache/7af8331bf1196ca28793bd1e8f6ecc7b/4/8/4850.jpg
Ugly. But I suppose that's a secondary concern for such discerning individuals.
I almost forgot, you could run a clamp-on front sight:
https://yhm.net/media/catalog/product/cache/1/image/1140x/040ec09b1e35df139433887a97daa66f/9/3/9396-3_1.jpg
https://www.wolverinesupplies.com/images/items/Fullsize/AMLEU0240MPKIT.jpg
I hope this exercise was useful for folks other than just me.
https://palmettostatearmory.com/media/catalog/product/cache/7af8331bf1196ca28793bd1e8f6ecc7b/4/8/4850.jpg
Ugly. But I suppose that's a secondary concern for such discerning individuals.
I used a similar device back in the day for mounting my big ass flashlight.
MontanaMarine
08-08-20, 11:46
Here's why I like the 16" mid, or the 14.5" carbine with the FSB.
https://i.imgur.com/wnwRRJ8.jpg
lordmorgul
08-08-20, 12:28
Aero Precision Gen2 Quad, 20” Rifle length FSB WOA Service Rifle barrel. (Rubber tape crown protector)https://uploads.tapatalk-cdn.com/20200808/7502fc26e033922fdb17a291e294d374.jpg
https://uploads.tapatalk-cdn.com/20200808/56772da8a21176d8147d2f061d2d9e9e.jpg
https://uploads.tapatalk-cdn.com/20200808/0b9eff85c6253a8af3ac4637dd7a3591.jpg
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
Is this any good?
https://botach.com/kley-zion-bayonet-lug-mount/
63349
63350
Wouldn't you want a bit more clearance than that to keep it free floating?
https://uploads.tapatalk-cdn.com/20200808/56772da8a21176d8147d2f061d2d9e9e.jpg
lordmorgul
08-08-20, 12:39
And then the EMP hit
Yes but ACOGs are still working :-)
Granted I don’t have any of those. So have irons.
But my etched reticle prism sights and LVPOs are still working in daylight and any backlighting.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
ColtSeavers
08-08-20, 12:43
Aero Precision Gen2 Quad, 20” Rifle length FSB WOA Service Rifle barrel. (Rubber tape crown protector)https://uploads.tapatalk-cdn.com/20200808/7502fc26e033922fdb17a291e294d374.jpg
https://uploads.tapatalk-cdn.com/20200808/56772da8a21176d8147d2f061d2d9e9e.jpg
https://uploads.tapatalk-cdn.com/20200808/0b9eff85c6253a8af3ac4637dd7a3591.jpg
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
I'd have cut one more notch back on the top rail, and down to the second row of lightning cuts just above the side rails along the sides.
lordmorgul
08-08-20, 12:45
Wouldn't you want a bit more clearance than that to keep it free floating?
Yes maybe. With service rifle comp firing schedule no, it doesn’t seem to make any contact I can detect on the “aluminum black” cut surfaces. I’m sure depends on the rail quality and attach (Aero Enhanced upper integrated rail mount is pretty solid and aligned). With a faster firing schedule and less attention to rail mount yes, and if making it for general FSBs rather than this WOA clamp design exactly...
But it’s an idea available to anyone.
(And likely non-compliant at any SR comps but regional matches where I shoot)
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
Its kinda funny to me that everyone is worried about their backup sights being mounted on a rail with all the DBALS etc...Ive seen mounted on rails...
justin_247
08-08-20, 22:15
Its kinda funny to me that everyone is worried about their backup sights being mounted on a rail with all the DBALS etc...Ive seen mounted on rails...
Looking at this thread, I have a feeling that those who care about having an FSB don't really use laser aiming devices, or at least don't consider them to be a primary consideration.
Diamondback
08-08-20, 23:03
Speaking for myself, I'll use a laser or optic if I have one, but anything run by a battery can be visited by the Gremlins. I run irons as a "They Absolutely HAVE To Work" last-ditch backup (never mind that I tend to use military-issue configurations as "clone templates" and almost all my builds are adapted to personal needs from those baselines), so I want them absolutely failsafe--the only reason I have a folder rear on my Mk 18-ish is that my preferred sight manufacturer doesn't make a fixed and never replied to my email asking if they could suggest a way to rig it for "permanent up," and the only reason my M4 has a folder is it's what the USMC "cookbook" I was trying to replicate requires.
vicious_cb
08-09-20, 00:30
Just so its clear to anyone else who happens on this thread in the future, its pure stupidity to take a hacksaw to your rail just to make a FSB fit. In this case to meet some match requirement Ill give it a pass but if you're thinking about doing this on serious use rifle: don't. You are compromising the strength and rigidity of the rail when you start taking chunks off it that some engineer who designed it thought should have been there in the first place.
justin_247
08-09-20, 11:42
Just so its clear to anyone else who happens on this thread in the future, its pure stupidity to take a hacksaw to your rail just to make a FSB fit. In this case to meet some match requirement Ill give it a pass but if you're thinking about doing this on serious use rifle: don't. You are compromising the strength and rigidity of the rail when you start taking chunks off it that some engineer who designed it thought should have been there in the first place.
Numerous people on this forum, including senior members and industry professionals, have cut into their rails and modified them. It's not a big deal, especially if you're only modifying the ends.
ColtSeavers
08-09-20, 11:47
Numerous people on this forum, including senior members and industry professionals, have cut into their rails and modified them. It's not a big deal, especially if you're only modifying the ends.
Seriously, just stay within existing cuts/support sections and round out the edges. It's an aluminum tube...
lordmorgul
08-09-20, 15:38
Just so its clear to anyone else who happens on this thread in the future, its pure stupidity to take a hacksaw to your rail just to make a FSB fit. In this case to meet some match requirement Ill give it a pass but if you're thinking about doing this on serious use rifle: don't. You are compromising the strength and rigidity of the rail when you start taking chunks off it that some engineer who designed it thought should have been there in the first place.
I’m not an aluminum structure subject matter expert, but I am an engineer and get sufficient cross-disciplinary exposure to confidently say I’m not the least bit concerned about that. What do you expect that I’m doing with that rail even if it is a hard use gun? It’s not a pry bar. Use your own judgement.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
vicious_cb
08-09-20, 18:06
I’m not an aluminum structure subject matter expert, but I am an engineer and get sufficient cross-disciplinary exposure to confidently say I’m not the least bit concerned about that. What do you expect that I’m doing with that rail even if it is a hard use gun? It’s not a pry bar. Use your own judgement.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
Do you really trust a majority of the AR people to actually do this correctly? What if they start mounting stuff to the front end like bipods and foregrips and start applying lever forces? At least with factory cutout rails they've actually done the testing beforehand.
ColtSeavers
08-09-20, 19:21
Do you really trust a majority of the AR people to actually do this correctly? What if they start mounting stuff to the front end like bipods and foregrips and start applying lever forces? At least with factory cutout rails they've actually done the testing beforehand.
Isn't it both the right and responsibility of the individual to choose whether their skill level is up to par for any endeavor they choose?
Looking at this thread, I have a feeling that those who care about having an FSB don't really use laser aiming devices, or at least don't consider them to be a primary consideration.
That (for me) is true. But if I did have a dbal, the FSB would act like a roll cage to some extent where an impact to the front sight doesn't jar the rail. My experience was that my rail mount sight smashed and so did the top rail. Double screwed.
If a Dbal got mis-aligned, you'd still have a functional sight system with the FSB. If a rail gets wacked with no FSB, then everything on the rail is messed up.
I know these may be far fetched scenarios to some, but there's some logic to it.
That (for me) is true. But if I did have a dbal, the FSB would act like a roll cage to some extent where an impact to the front sight doesn't jar the rail. My experience was that my rail mount sight smashed and so did the top rail. Double screwed.
If a Dbal got mis-aligned, you'd still have a functional sight system with the FSB. If a rail gets wacked with no FSB, then everything on the rail is messed up.
I know these may be far fetched scenarios to some, but there's some logic to it.
My DBAL guns have THREE sighting systems. DBAL, Red Dot, Backup Irons. Now, a good whack to the rail could disable both the DBAL and the front sight of my irons....But that leaves a "bombproof" red dot- receiver mounted, as a back up. At some point, redundancy gets into the realm of fantasy land. Sure, somewhere there is that one guy that lost all three sighting systems in the middle of a shit storm of bullets- but, I'll take my chances on it not being me.
Hammer_Man
08-13-20, 15:14
In the world of hypotheticals, I feel that a properly pinned on FSB is the most bomb proof front sight available. It would take a significant blow to a rifle to knock one out of alignment. I would venture that a hit that significant would probably disable any electronic sight, laser aiming device, and perhaps the rifle itself.
In the world of hypotheticals, I feel that a properly pinned on FSB is the most bomb proof front sight available. It would take a significant blow to a rifle to knock one out of alignment. I would venture that a hit that significant would probably disable any electronic sight, or laser aiming device.
I will say this, MANY of my rifles start out with an A2 or Carbine (F) type front sight. I have it cut off and a rail installed over it. Extra work? Yup, but absolutely the most bomb proof gas block design bar none...and, it's essentially free minus a little grinder work....
I will say this, MANY of my rifles start out with an A2 or Carbine (F) type front sight. I have it cut off and a rail installed over it. Extra work? Yup, but absolutely the most bomb proof gas block design bar none...and, it's essentially free minus a little grinder work....
As a card carrying fan of bomb proof, my opinion is that once you chop an FSB down, the need for pinning is monumentally reduced because there's nothing protruding to take an impact.... and the chopped block is usually under a rail.
As a card carrying fan of bomb proof, my opinion is that once you chop an FSB down, the need for pinning is monumentally reduced because there's nothing protruding to take an impact.... and the chopped block is usually under a rail.
From my understanding when Crane held the RECCE trials there were two finalists. One had a pinned gas block, the other did not. In the final stages of testing the rifle whose block was not pinned, had the block walk and it began to malfunction, they lost. This is why- supposedly- Mr. Leclair at Centurion insists on pinning all his gas blocks- and one reason I buy his guns!
From my understanding when Crane held the RECCE trials there were two finalists. One had a pinned gas block, the other did not. In the final stages of testing the rifle whose block was not pinned, had the block walk and it began to malfunction, they lost. This is why- supposedly- Mr. Leclair at Centurion insists on pinning all his gas blocks- and one reason I buy his guns!
Yep. We've had a block slide. But it wasn't dimpled. I'm completely fine with a dimple and set screw. I'll even stake a set screw.
I do agree that pinning is far superior, my lo pro block guns are more likely to be long range shooters or just funzy guns.
davidjinks
08-14-20, 17:29
All of my rifles have FSB. I see no reason to get rid of them. They work.
In 2007 (https://www.m4carbine.net/showthread.php?6709-Fighting-AR-s-and-front-sights) most were in favor of (unshaved) front sight bases on serious guns, nearly unanimously in the case of unmagnified optics. (The thread then digressed into the value of pinning.) Browsing the photo threads today I see a lot of guns without a FSB. Do serious builds by the most knowledgeable still use FSB's?
love the fsb, a must for me on my go to rig although I have set ups without
vicious_cb
08-15-20, 23:43
From my understanding when Crane held the RECCE trials there were two finalists. One had a pinned gas block, the other did not. In the final stages of testing the rifle whose block was not pinned, had the block walk and it began to malfunction, they lost. This is why- supposedly- Mr. Leclair at Centurion insists on pinning all his gas blocks- and one reason I buy his guns!
Id like to see the source on this, since Crane adopted the Mk12 SPR. AFAIK the Mk12 to this day still doesnt have a pinned gas block, and unlike the SOPMODs or URGIs the gas block sits outside the rail.
Mine have a FSB but I shoot irons mostly...
Five_Point_Five_Six
08-18-20, 13:58
I have this strange desire to do a MRP mock Dissipator with a 14.5" MRP barrel.
Glock9mm1990
08-18-20, 14:21
63442
Not only FSB’s in 2020, but 20” barrels and A2 stocks as well.
Five_Point_Five_Six
08-18-20, 14:22
63442
Not only FSB’s in 2020, but 20” barrels and A2 stocks as well.
I ain't mad at it.
Glock9mm1990
08-18-20, 14:24
I ain't mad at it.
This 20” BCM upper with Trijicon TA31F-G is my favourite rifle I own.
Five_Point_Five_Six
08-18-20, 14:57
This 20” BCM upper with Trijicon TA31F-G is my favourite rifle I own.
I'm almost to the point in my life where I either want a 10.5/11.5" with the option to suppress or a 20". I'm finding less and less desire to shoot anything 14.5 or 16". I either want them short and quiet or long with all the FPS.
Glock9mm1990
08-18-20, 16:01
I'm almost to the point in my life where I either want a 10.5/11.5" with the option to suppress or a 20". I'm finding less and less desire to shoot anything 14.5 or 16". I either want them short and quiet or long with all the FPS.
I was in the same position as you, ether a 11.5” or a 20”. I went with the 20” and I am glad I did.
I thought the answer to "ether a 11.5” or a 20”" was "Yes." ;)
I'm almost to the point in my life where I either want a 10.5/11.5" with the option to suppress or a 20". I'm finding less and less desire to shoot anything 14.5 or 16". I either want them short and quiet or long with all the FPS.
Coming to the same conclusion.
I'm partial to the 20" bbl and A2 stock, because that's primarily what I carried during OSUT.
Five_Point_Five_Six
08-19-20, 11:22
I was in the same position as you, ether a 11.5” or a 20”. I went with the 20” and I am glad I did.
No I mean having both.
FSB’s are great and still very serviceable in 2020. I’ve wondered about rails a lot in the past, and my favorite setup currently is a 10.3” RAS setup. I picked up a Daniel defense upper with a pinned block; I haven’t shot it much, but I have a hard time imagining it being any worse than a FSB setup. Shaved block on an 11.5” FBI barrel isn’t going anywhere. I assembled an upper that had the gas block walk some, so I aligned it again, shot some rounds through it, checking it and torquing a little while it was hot. No idea if that’s good or bad but it worked. I wouldn’t trust my life to an unpinned block though. I would trust rail mounted irons.
FSB’s are great and still very serviceable in 2020. I’ve wondered about rails a lot in the past, and my favorite setup currently is a 10.3” RAS setup. I picked up a Daniel defense upper with a pinned block; I haven’t shot it much, but I have a hard time imagining it being any worse than a FSB setup. Shaved block on an 11.5” FBI barrel isn’t going anywhere. I assembled an upper that had the gas block walk some, so I aligned it again, shot some rounds through it, checking it and torquing a little while it was hot. No idea if that’s good or bad but it worked. I wouldn’t trust my life to an unpinned block though. I would trust rail mounted irons.
It’s okay as long as you machine or drill small divots for the adjustable gas block/FSP set screws: and you do not over torque your set screws. Otherwise you will almost certainly deform the barrel while its hot as you tighten the set screws into the barrel. It will permanently alter the bore and effect pressure and rifling. It’s best to taper pin any gas block and by milling it to the barrel while aligned properly. Two taper pins as used in the military FSP is vastly superior to alternatives.
I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.
ColtSeavers
08-23-20, 12:14
I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.
How dare you disparage set screw gas blocks in dimples by providing a first hand account of a failure.
You are supposed to anecdotally attack clamp on gas blocks.
I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.
You forgot to use high temp sleeve retainer when you installed the block. 🤣🤣 😝
Also remember to clean all oil off a steel gas block and barrel it will oxidize and hold tighter. Most set screw gas blocks come with too soft set screws. And yes I will not use them period: after going through all the process you end up with a gas block that is inferior to a pinned gas block.
How dare you disparage set screw gas blocks in dimples by providing a first hand account of a failure.
You are supposed to anecdotally attack clamp on gas blocks.
Lol. Forgive me!
Yeah, my rifle shopped cycling and it took me a minute to figure out why. I mean, it couldn't possibly be the gas block, so why even look at it...but it was. And since it would shifted radially, as opposed to moving down the barrel, it was even harder to pick up on because the set screw was still providing tension. So it would clock side to side under recoil, sometimes being aligned, and when I first looked did not appear to be off. That particular barrel has 5190 rounds through it, which leads me to believe most people will never discover this problem if it can be a problem. It's off getting pinned right now.
You forgot to use high temp sleeve retainer when you installed the block. 🤣🤣 😝
Also remember to clean all oil off a steel gas block and barrel it will oxidize and hold tighter. Most set screw gas blocks come with too soft set screws. And yes I will not use them period: after going through all the process you end up with a gas block that is inferior to a pinned gas block.
True, but high temp sleeve retainer is not part of the equation that is usually recommended. You're average guy, including me, has been taught that red loctite is all you need...but I digress. I'm betting I somehow failed to properly prep the parts making the use of any adhesive at all semi-pointless, although cleaning parts is part of my build process.
Five_Point_Five_Six
08-23-20, 14:20
I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.
Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.
You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.
You are supposed to anecdotally attack clamp on gas blocks.
That does seem funny to me. I have never seen set screws used to attach the stem of a hard use MTB. If clamp-on attachment is not secure enough set screw attachment surely isn't. But I like my pinned FSB.
Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.
You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.
What's your set screw staking method?
I also have considered to use rocksett going forward.
What's your set screw staking method?
I also have considered to use rocksett going forward.
I use a starter punch to make four small stakes.
Loctite 2422 Medium Strength claims 650*. A tube will last a long time.
You forgot to use high temp sleeve retainer when you installed the block. ���� ��
Also remember to clean all oil off a steel gas block and barrel it will oxidize and hold tighter. Most set screw gas blocks come with too soft set screws. And yes I will not use them period: after going through all the process you end up with a gas block that is inferior to a pinned gas block.
Which sleeve retainer do you use?
Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.
You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.
Pictures! (Please.)
I use a starter punch to make four small stakes.
Loctite 2422 Medium Strength claims 650*. A tube will last a long time.
I'll order some. Could you post a picture of your staking?
Is there any reason we don't all use rocksett for this application?
I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.
I'm curious to know a little more about this. Was the gas block under a rail? And did it just spontaneously shoot loose?
Five_Point_Five_Six
08-23-20, 16:40
What's your set screw staking method?
I also have considered to use rocksett going forward.
Spring loaded punch or a regular punch and a hammer. Rocksett will work, but will need to be soaked in water for days to free it up after prolonged use, at least in the experiences I have removing things secured with Rocksett.
Which sleeve retainer do you use?
Pictures! (Please.)
I'll order some. Could you post a picture of your staking?
Is there any reason we don't all use rocksett for this application?
I don't have any photos, and can't take any because the only uppers I have that don't have a FSB are MRP barrels and those are pressed and pinned in place.
I'm curious to know a little more about this. Was the gas block under a rail? And did it just spontaneously shoot loose?
Yes. And after checking my toolbox, they are correct in that my "red loctite" is only rated to 300 degrees...making it a matter of time until failure of the adhesive. I was sighting in a scope and my rifle stopped picking up new rounds (short stroking). I though it was the ammo, so I switched and it worked for a few rounds and resumed short stroking. Everything seemed fine. Then I tried a few more times and when I double checked the gas block it was slightly clocked. The set screw ended up being backed out enough to rotate but not so much it wasn't catching on the edge of the barrel's dimple. It had probably been loose for a short while before moving enough to induce a malfunction.
Which sleeve retainer do you use?
Pictures! (Please.)
I'll order some. Could you post a picture of your staking?
Is there any reason we don't all use rocksett for this application?
Permatex High Temp Sleeving Compound or Loctite 640. Good to 400F.
Jet-Lube makes Deacon 770L which is good to 950F.
Rocksett is better if you can find it. Good to 2000F so they say.
A FSP will hit 750F during heavy fire so Rocksett is the way to go if you’re not pinning it. But the crappy set screws will probably fail and I have seen Rocksett fail on a number of muzzle devices. Deacon 770L would be my choice if the gas block is a bit loose. Rocksett or 640 if it’s tight. I have not had 640 fail on my FBI HRT SAWHB FSP that was bubbad by the previous owner.
I would like to try high temp Rocksett and add it to my armorers kit.
Yes. And after checking my toolbox, they are correct in that my "red loctite" is only rated to 300 degrees...making it a matter of time until failure of the adhesive. I was sighting in a scope and my rifle stopped picking up new rounds (short stroking). I though it was the ammo, so I switched and it worked for a few rounds and resumed short stroking. Everything seemed fine. Then I tried a few more times and when I double checked the gas block it was slightly clocked. The set screw ended up being backed out enough to rotate but not so much it wasn't catching on the edge of the barrel's dimple. It had probably been loose for a short while before moving enough to induce a malfunction.
Thanks for the additional details.
Permatex High Temp Sleeving Compound or Loctite 640. Good to 400F.
Jet-Lube makes Deacon 770L which is good to 950F.
Rocksett is better if you can find it. Good to 2000F so they say.
A FSP will hit 750F during heavy fire so Rocksett is the way to go if you’re not pinning it. But the crappy set screws will probably fail and I have seen Rocksett fail on a number of muzzle devices. Deacon 770L would be my choice if the gas block is a bit loose. Rocksett or 640 if it’s tight. I have not had 640 fail on my FBI HRT SAWHB FSP that was bubbad by the previous owner.
I would like to try high temp Rocksett and add it to my armorers kit.
Thank you. I have always made sure to use high quality set screws. I do have a decent sized thing of rocksett, but I'm also aware that it is only good for a few months after it's been opened. I'll have to replace set screws with that or the 2422 I ordered. Unfortunately, the only sleeve retainer I have is Loctite 620. Regardless, I'll get the affected gas blocks pinned in the meantime and use the proper thread locker at that point.
Thanks for the additional details.
Happy to provide them. Hopefully this serves as a resource for those learning with me today. For whatever reason, I had believed I did have the high temp stuff, which I certainly didn't.
I would still love to see what staked set screws look like.
https://www.google.com/search?q=staked+gas+block.screws&client=safari&hl=en-us&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiO_vaYxLPrAhWrTN8KHckQCWcQ_AUoAnoECBYQAg&biw=320&bih=454&dpr=2#imgrc=7Eq1Y8S730ZD1M
Not my pic
https://www.google.com/search?q=staked+gas+block.screws&client=safari&hl=en-us&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiO_vaYxLPrAhWrTN8KHckQCWcQ_AUoAnoECBYQAg&biw=320&bih=454&dpr=2#imgrc=7Eq1Y8S730ZD1M
Not my pic
Thank you. I saw that when I searched and wondered if it was a good representation.
https://www.google.com/search?q=staked+gas+block.screws&client=safari&hl=en-us&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiO_vaYxLPrAhWrTN8KHckQCWcQ_AUoAnoECBYQAg&biw=320&bih=454&dpr=2#imgrc=7Eq1Y8S730ZD1M
Not my pic
I would probably stake them at three locations due to their size and softness. You really do not want anything too hard. More so that the set screw fits into the dimples you machine into the barrel properly. Some set screws have the little step at the business end. Most I have used were too wide at the end and too soft. The best are the carbon steel set screw that tend to oxidize because they seem to lock up well due to oxidation. Stainless is slippery and will chew into the barrel. The soft stuff is good until it deforms under heat. I like the Super Gas Block setup because the set screws become a part of the alignment process. When you set the screws and ensure alignment and settling of the set screws into the dimples, it provides a fairly solid foundation to mill or drill a hole for the stainless coil pin. Still it’s easy to screw it up if you don’t know what your are doing. To me it’s easier to drill a FSP, taper, and pin it. I like to see a Badger gas block taper pinned, you know it’s solid and still better than two set screws and a large coil pin. Machine skills are truly the foundation to exceptional smith work. The 1911 smiths that make legendary 1911s are all expert machinists.
I would probably stake them at three locations due to their size and softness. You really do not want anything too hard. More so that the set screw fits into the dimples you machine into the barrel properly. Some set screws have the little step at the business end. Most I have used were too wide at the end and too soft. The best are the carbon steel set screw that tend to oxidize because they seem to lock up well due to oxidation. Stainless is slippery and will chew into the barrel. The soft stuff is good until it deforms under heat. I like the Super Gas Block setup because the set screws become a part of the alignment process. When you set the screws and ensure alignment and settling of the set screws into the dimples, it provides a fairly solid foundation to mill or drill a hole for the stainless coil pin. Still it’s easy to screw it up if you don’t know what your are doing. To me it’s easier to drill a FSP, taper, and pin it. I like to see a Badger gas block taper pinned, you know it’s solid and still better than two set screws and a large coil pin. Machine skills are truly the foundation to exceptional smith work. The 1911 smiths that make legendary 1911s are all expert machinists.
Are you trying to deform the set screws or the inside threads of the gas block? The set screws will be recessed by the time they are fastened down.
Are you trying to deform the set screws or the inside threads of the gas block? The set screws will be recessed by the time they are fastened down.
You are creating proud marks with a sharp punch so that it locks the material from the set screw's edge to the gas block. On a small fastener like gas block set screws, you should probably "stake" them three equal distance locations around each set screw. Starrett 264E is what I use for staking the castle nuts to the extensions: it also has a sharp tip so you can do fine work like set screws on a gas block.
As far as drilling/machining dimples for set screw in the barrel, you want the dimples to be sized so that the set screws business end seats into the dimple with minimal torque: too much torque will deform the barrel when it gets hot. I see wide and soft set screws being used on gas block kits, and you would have to machine really large dimples for them to work properly and I do not like this. The metal you use for set screws should be able to handle 1000F without deforming to be safe. There are many, many options. You would be better using stainless set screws for heat, but they will be difficult to stake, and they do not lock in well with retaining compounds.
In the end I would just buy a jig, end mill bit, high quality drill bits, and a taper bit with hand tool, and do it right. You'll also want a good sulfur cutting oil (stinky), and use a moderate amount while cutting into the barrel. Always use a new set of taper pins, clean them with spirits so they have no oil on them or inside the FSP/gas block and barrel (they will oxidize a bit and lock up, and oil the outside when finished), use a nice heavy hammer to seat them well. You do not need a jig if you are handy, but it helps prevent alignment and location issues. I have managed to complete a stainless gas block without a jig, but it requires a lot of attention and finesse in my opinion. The bear for me in installing an FSP without a jig would be ensuring the pin locations are drilled so that they do not remove any more material form the barrel than necessary.
You are creating proud marks with a sharp punch so that it locks the material from the set screw's edge to the gas block. On a small fastener like gas block set screws, you should probably "stake" them three equal distance locations around each set screw. Starrett 264E is what I use for staking the castle nuts to the extensions: it also has a sharp tip so you can do fine work like set screws on a gas block.
As far as drilling/machining dimples for set screw in the barrel, you want the dimples to be sized so that the set screws business end seats into the dimple with minimal torque: too much torque will deform the barrel when it gets hot. I see wide and soft set screws being used on gas block kits, and you would have to machine really large dimples for them to work properly and I do not like this. The metal you use for set screws should be able to handle 1000F without deforming to be safe. There are many, many options. You would be better using stainless set screws for heat, but they will be difficult to stake, and they do not lock in well with retaining compounds.
In the end I would just buy a jig, end mill bit, high quality drill bits, and a taper bit with hand tool, and do it right. You'll also want a good sulfur cutting oil (stinky), and use a moderate amount while cutting into the barrel. Always use a new set of taper pins, clean them with spirits so they have no oil on them or inside the FSP/gas block and barrel (they will oxidize a bit and lock up, and oil the outside when finished), use a nice heavy hammer to seat them well. You do not need a jig if you are handy, but it helps prevent alignment and location issues. I have managed to complete a stainless gas block without a jig, but it requires a lot of attention and finesse in my opinion. The bear for me in installing an FSP without a jig would be ensuring the pin locations are drilled so that they do not remove any more material form the barrel than necessary.
I don't own a mill, so I'll leave that part to a professional. The uppers that still need pinning are headed to D.wilson this week. I'll figure out the staking on the remaining uppers. Thanks for the feedback.
I don't own a mill, so I'll leave that part to a professional. The uppers that still need pinning are headed to D.wilson this week. I'll figure out the staking on the remaining uppers. Thanks for the feedback.
In most cases the pros can do better. Like SA's FH to 16" service: it's really sexy. You can use an end mill on a drill press, it cuts edges better but you have to understand it requires finesse, slow feed, and cutting oil. Having a good drill press is beneficial. I grew up using the old cast drill press' owned by my father and uncle: they all had the big mill type clamps. One of my uncle's had a mill press which was really handy for custom fabricating of small parts and I used it on many of my guns successfully. A late family member who used to CNC, and had a ESD unit, and a number of other machines was able to make me a custom comp. for my 7.7mm before they were obtainable without spending a fortune to have one custom made. I'm sure your project will come out great, post pics!
I use a starter punch to make four small stakes.
Loctite 2422 Medium Strength claims 650*. A tube will last a long time.
Sorry for the necro. I ran across this thread while googling about FSB jigs, and realized I gave out bad info.
Loctite 2422 is meant for bolts 1/2”-3/4”, which set screws are not. The fact that it has worked for me might be coincidental, just like the people that get away with red on their Mk18/SDN-6.
FSB is still king for a gas block and front sight. You dont see them now because its much easier to pump out low pro long rail URG's. My old work is the perfect example, they didnt want to put in the time and effort so they killed off FSB options.
Sorry for the necro. I ran across this thread while googling about FSB jigs, and realized I gave out bad info.
Loctite 2422 is meant for bolts 1/2”-3/4”, which set screws are not. The fact that it has worked for me might be coincidental, just like the people that get away with red on their Mk18/SDN-6.
What have you been using lately?
Sorry for the necro. I ran across this thread while googling about FSB jigs, and realized I gave out bad info.
Thank you.
What have you been using lately?
Red, crosspins, stakes, hopes and dreams. I use the grippy tipped setscrews, single use, and dimple.
Once I put a pin in it, the rest is overkill and the threadlocker just keeps the screws from backing out while I drill.
FSB is still king for a gas block and front sight. You dont see them now because its much easier to pump out low pro long rail URG's. My old work is the perfect example, they didnt want to put in the time and effort so they killed off FSB options.
I still like the old SAW style shaved FSB's better than the majority of gas blocks.
titsonritz
04-08-22, 12:53
FSB is still king for a gas block and front sight. You dont see them now because its much easier to pump out low pro long rail URG's. My old work is the perfect example, they didnt want to put in the time and effort so they killed off FSB options.
My daughter has a SIONICS 16" LW with an FSB, I've told she'd better never sell it and if she does it better be to me.
FSB is still king for a gas block and front sight. You dont see them now because its much easier to pump out low pro long rail URG's. My old work is the perfect example, they didnt want to put in the time and effort so they killed off FSB options.
I'm glad I got one before they stopped. It's INSANE for me to think of cutting down a real FSB to accommodate some goofy long rail. Completely nuts!
I'm glad I got one before they stopped. It's INSANE for me to think of cutting down a real FSB to accommodate some goofy long rail. Completely nuts!
Not to me. In fact I would prefer it. A double pinned Shaved FSP>two set screws.
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I agree with the mounting being superior. That's common sense, but the idea of ruining an FSB is repulsive to me. It should be illegal!!!
It should be illegal!!!
Careful, some Democrat might hear you. :rolleyes:
Careful, some Democrat might hear you. :rolleyes:
I'd think they be all for emasculation of a firearm.
FSB is still king for a gas block and front sight. You dont see them now because its much easier to pump out low pro long rail URG's. My old work is the perfect example, they didnt want to put in the time and effort so they killed off FSB options.
I have a Patrol 0 with the FSB and it is hands down my favorite rifle. I was disappointed to see that model dropped.
I prefer fixed FSBs for shooting iron sights, but anything I intend to have a magnified optic on I prefer the front sight to fold out of the way. For this the Colt 6940's folding FSB and the pin on version of the A.R.M.S. #41 are my favorite.
My BCM 14.5" with FSB is still my go to rifle.
If you ares till running a red dot from 2007, you probably still want a fixed FSB. If you’re running a modern aimpoint I don’t see the need.
I feel like the discussion today is more of if it’s necasary to even put buis on a gun or not? Is a laser a back up or not?
I prefer eotech for night vision but don’t trust them and battery life still sucks. I use a fixed front on this gun. I feel like with an aimpoint buis are 200$ of do-dad on a gun that I’ll never use. I have them though, but certainly question it.
Another insight I have here is the other day my eotech fogged really badly and even after wiping it it came right back. It took about 10-15 minutes for the sight to acclimatize. In that time I couldn’t see my fixed front sight through it anyway. Just something to consider.
If you ares till running a red dot from 2007, you probably still want a fixed FSB. If you’re running a modern aimpoint I don’t see the need.
I feel like the discussion today is more of if it’s necasary to even put buis on a gun or not? Is a laser a back up or not?
I can see that approach too. My 10.5 has only the FSB and a ROMEO 5 with no rear sight. So even though I'm effectively running the gun with no BUIS system, I still want a real FSB and not some low pro.
(I do have a few low pro guns, but my serious stuff has the original FSB)
Half my guns have an FSB, red dots and a back up rear sight....
I prefer fixed FSBs for shooting iron sights, but anything I intend to have a magnified optic on I prefer the front sight to fold out of the way. For this the Colt 6940's folding FSB and the pin on version of the A.R.M.S. #41 are my favorite.
When magnified more than a little it disappears and you can't see it anyway. No need to fold or flip anything out of the way.
When magnified more than a little it disappears and you can't see it anyway. No need to fold or flip anything out of the way.
I've heard that repeated through the centuries, but it has not been that way in my experience looking through my 4x ACOGs. The FSB shows up as a big blurry blob that's very distracting.
Looking through unmagnified dot sights at the FSB isn't nearly as annoying, but I'd still prefer a folding front sight with those as well.
I have a 4x Burris prism scope on one of my 16” AR’s with a FSB. I can’t see the FSB at all even if I try to find it.
Edit: I was responding to 556cliff
I have a 4x Burris prism scope on one of my 16” AR’s with a FSB. I can’t see the FSB at all even if I try to find it.
Edit: I was responding to 556cliff
That is surprising to hear. Maybe it's just an ACOG thing?
Maybe so I have no experience with owning an acog and wasn’t issued on in the military
That is surprising to hear. Maybe it's just an ACOG thing?
Could be. Some of them are known for their exceptional field of view. I'm to the point I purposely align the shadow with the bottom of the reticle to keep my groups from wandering.
I have only one AR with a FSB. The next one and the one after will have a FSB.
All of my AR's have the FSB. One has a Aimpoint Comp M4 with SIG Juliet 4X magnifier, the other a ACOG 3.5. I don't notice the front sight unless I'm looking for it.
I can find the FSB shadow in ACOGs if I look for it, but when shooting I don't notice it.
When magnified more than a little it disappears and you can't see it anyway. No need to fold or flip anything out of the way.
The FSB disappears, but it's still there, reducing light that enters the optic and blocks your view for hold overs. It reduces the optical quality to that of an 80's Tasco
Rifleman_04
04-12-22, 17:31
Nitpicks from the living room couch.
I’ve never noticed the fsb while using my guns with an acog.
Nitpicks from the living room couch.
I’ve never noticed the fsb while using my guns with an acog.
I'm glad for you. But don't assume my nits are picked from a living room couch unless that couch is in the middle of the wilderness.
I'm glad for you. But don't assume my nits are picked from a living room couch unless that couch is in the middle of the wilderness.
Who says you couldn't have drug an old couch out there???
Might have been one not fit for your home but still not too nasty to toss entirely so....
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