View Full Version : Centurion 12.5" Suppressed: Adjustable Block?
Does anyone have experience running a Centurion 12.5" suppressed? Is an adjustable block necessary, or is the port small enough?
I plan on running it suppressed ~50% of the time. It will be on an A5 equipped lower.
No adjustable gas block fits the Hodge Wedge Lock rail I plan on using.
jerrysimons
10-03-16, 02:36
Screw! I missed the boat on the Hodge 11.5" rail! What to sell it?
Also, why does Mega spec their version in length so oddly and then not list the actual length like it is some type of secret!? 12.6" actual OAL 12" rail, how many people buy a cutting edge $300 dollar free float rail just to put behind a rifle length FSB? No 15" rail but a 16.6" actual OAL 16" rail??? At least the 9" at 9 5/16" is a good match for 10.3-10.5" barrels.
The good news is the only adj gas block that fits under the rail is the only gas block fit enough to put under it, IMO. SLR Rifleworks Sentry 7 is the best. Nope, see below
I am considering this same question though. Leaning towards BLack River Tactical gas-block insert/ microtune gas-block once I figure out a good port size for a 12.5" carbine barrel.
Defaultmp3
10-03-16, 08:30
I plan to assemble an upper with a Centurion 12.5" + Hodge Wedge Lock rail. Unfortunately, no adjustable gas block fits under this rail. The only gas block that I know of that definitely clears is the SLR GB7.Is the Hodge somehow different than the Mega in interior dimensions? I was told by Mega that most low profile gas blocks would fit under their Wedge Lock.
jerrysimons
10-03-16, 08:41
Is the Hodge somehow different than the Mega in interior dimensions? I was told by Mega that most low profile gas blocks would fit under their Wedge Lock.
They both have a 1.225" interior diameter according to published specs. I have a Mega Wedge Lock I will shortly verify if it fits with the SLR Rifleworks Sentry 7 GB. Pretty sure I have read it will fit.
Also I was going off the op's wording but if the Sentry 7 fits under the rail a Syrac adjustable gas block will too.
Defaultmp3
10-03-16, 08:54
They both have a 1.225" interior diameter according to published specs. I have a Mega Wedge Lock I will shortly verify if it fits with the SLR Rifleworks Sentry 7 GB. Pretty sure I have read it will fit.
Also I was going off the op's wording but if the Sentry 7 fits under the rail a Syrac adjustable gas block will too.Let us know what you find out. I have a Wedge Lock 10.75", and was hoping to jam a Govnah into there; MicroMOA eyeballed the Megas and said the 2 plate version would probably fit, but I was willing to further machine down the gas block anyway to make sure it'd fit (well, pay someone else to machine it down, anyway).
NO adjustable block fits under the Wedge Lock handguard.
The SLR GB7 is NOT adjustable.
Defaultmp3
10-03-16, 10:29
NO adjustable block fits under the Wedge Lock handguard.Source? The SLR 7 Set Screw has been used in Centurion Arms CMRs no problem, and that's got a 1.12" ID.
Source? The SLR 7 Set Screw has been used in Centurion Arms CMRs no problem, and that's got a a 1.12" ID.
I talked to Hodge, SLR, and Weapon Outfitters.
Hodge Wedge Lock ID is smaller than the CMR
Defaultmp3
10-03-16, 10:40
I talked to Hodge, SLR, and Weapon Outfitters.
Hodge Wedge Lock ID is smaller than the CMRSo the Hodge Wedge Lock does actually have a different ID than the Mega variant? Mega's website shows that their Wedge Lock has an ID of 1.225". Or is it another part of the rail that is limiting gas blocks, e.g., height, gas tube slot, etc.?
I guess I could break my Hodge Wedge Lock out of its packaging and grab a set of set of calipers and see the exact interior.
SOVIETsilence
10-03-16, 10:48
Scooter, I have a 12.5" centurion barrel and run it suppressed with an M4-2000. I don't know the port diameter, but it is definitely appropriately sized. It is quite a soft shooter with imi xm193 and a standard carbine receiver extension with h3 buffer. I used the centurion low profile gas block to fit under my cmr.
jerrysimons
10-03-16, 11:25
Maybe TexasJim will roll in and spill the beans on the exact inner diameter of the Hodge Defense Wedge Lock Rail. Mega says their version is 1.225" inner diameter on their web site, Hodge may be smaller than MEGA's, IDK. I have a MEGA 9" rail on a 10.5" barrel mocked up. I just test fitted both SLR Riflework's Sentry 7 and a Syrac Ordinance's Gen 2 adjustable gas blocks. The Syrac fits inside the rail ALL DAY. The SLR Rifleworks clears the rail but only by a hair less than a millimeter where the screw holds the leaf spring in place. It clears but it is too close for comfort with barrel whip and rail flex factored. Now you could clearance either the rail or the face of the screw on the GB or both and it would be fine but that is custom fitting and maybe a little bit jerry rigging. For sure the first MLOK slot on the leaf spring side of the rail would not be usable with the SLR Sentry 7 as the carbine length gas with 9 5/16" OAL rail puts the GB right under the first MLOK slot (Hodge Defense rails have one slot, MEGAs have two). I should have tested the MLOK fitment with both gas blocks also but I will get back to that. If I had to guess the more I think about it I would say that the anti compatibility warnings the op heard focus on MLOK compatibility at slot over the gas block and not necessarily gas block clearance inside the rail. Like I said, the Syrac Gen 2 adj GB cleared inside the MEGA Wedge Lock rail all day long. The SLR Rifleworks Sentry 7 kind of cleared.
Pics to come.
I don't know the ID.
I talked to SLR on the phone, and Hodge on FB.
Both confirmed that SLR makes the GB for Hodge.
SLR told me that only the non adjustable GB7 would fit.
I have a Syrac on the way, so we'll see.
Does anyone have experience running a Centurion 12.5" suppressed? Is an adjustable block necessary, or is the port small enough?
I plan on running it suppressed ~50% of the time. It will be on an A5 equipped lower.
I have this barrel on my go-to SBR build. Mine is ported pretty small (0.065", measured with pin gages) and shoots quite soft. The lower has an A5-H3 buffer with a Tubbs flatwire AR-10 spring. I run it with a SiCo Omega part of the time and there is very minimal gas to the face and recoil is quite controllable. Without the can, I run an ASR brake on the gun and it recoils like a loud .22LR rifle.
If you're only plan on running suppressed 50% of the time, just run a regular gas block. If you find that it's a little too much for your taste, try the BRT gas port restrictors (as suggested) or the Baby Govnah from MicroMOA (standard low pro gas black where you drill your own port size) and tune it for your combination.
I'm temporarily using a TBAC 30P-1 on my Centurion 12.5" with an A5 equipped lower and the recoil is more than a 16" middy (a given) but not bad.
The last I heard, the centurion 12.5 was .065 gas port compared to .071-.076 for others.
If I were going to run a centurion 12.5 suppressed I would just leave if as is.
Sent from my iPhone using Tapatalk
The last I heard, the centurion 12.5 was .065 gas port compared to .071-.076 for others.
If I were going to run a centurion 12.5 suppressed I would just leave if as is.
Sent from my iPhone using Tapatalk
That's what I've been thinking.
I am considering this same question though. Leaning towards Black River Tactical gas-block insert/ microtune gas-block once I figure out a good port size for a 12.5" carbine barrel.
We've updated the product options on the Custom Tune Gas Port so you can enter the relevent parameters and we'll pick the best size for the application.
Otherwise, just drop us an email info@BRT and we can provide a solid recommendation.
The .065" gas ported 12.5" AR with full port pressure ammunition with a normal chamber and bore is one of my best options to fall back to for a 5.56 SBR. With full port pressure ammunition with a possible can, you can reduce that size, but that size depends a lot on the can involved.
The .065" gas ported 12.5" AR with full port pressure ammunition with a normal chamber and bore is one of my best options to fall back to for a 5.56 SBR. With full port pressure ammunition with a possible can, you can reduce that size, but that size depends a lot on the can involved.
Suppressor is a SF SOCOM-RC.
Training ammo is XM193.
Hunting ammo is Federal Fusion 62gr.
I do not know about the port pressure for that hunting ammo. I would tend not to opening up the port of a conventional Colt 14.5"ish .0625" port for a cut down 12.5" 5.56 port for that can only with M193. There are action types and mass that can certainly work well with this.
jerrysimons
10-03-16, 21:44
OP, sorry to go off on a corollary. Sounds like you are good to go with a 12.5" Centurion barrel, pin the Hodge recommended SLR and rock on. It is good to hear Centurion barrels are moderatly ported. I am somewhat partial to Noveske barrel profiles but I have to deal with their gapping gas ports. The port on my 10.5" light shorty is .083"!
Pics explained above
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/3C97BEBA-2F83-4A1F-9C2A-AAFF87A5AF53_zps54xi4zl1.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/3C97BEBA-2F83-4A1F-9C2A-AAFF87A5AF53_zps54xi4zl1.jpg.html)
Syrac Gen 2
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/283EE923-D37C-4C68-8D0A-C3168CD8E5FD_zpsplzqfw9m.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/283EE923-D37C-4C68-8D0A-C3168CD8E5FD_zpsplzqfw9m.jpg.html)
SLR Rifleworks Sentry 7
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/5EAB9198-4A5B-4422-8FD4-7ECCEDADFE26_zpsya8lgjmm.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/5EAB9198-4A5B-4422-8FD4-7ECCEDADFE26_zpsya8lgjmm.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/1B33A9D3-DDF6-467F-943B-B4B1FF1E0215_zpsajti2olu.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/1B33A9D3-DDF6-467F-943B-B4B1FF1E0215_zpsajti2olu.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/21F8ADB0-0FCF-4A1B-95D2-4D39873864B4_zpsdohx74mm.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/21F8ADB0-0FCF-4A1B-95D2-4D39873864B4_zpsdohx74mm.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/939DB44F-73C5-4D83-99D8-FE0348307F78_zps60lfpb7p.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/939DB44F-73C5-4D83-99D8-FE0348307F78_zps60lfpb7p.jpg.html)
So, SLR and Syrac adjustable blocks fit?
This is very strange considering three different sources, including SLR and Hodge, both said that it wouldn't work.
Is that an MUR? Is it drilled for the anti-rotation pin?
jerrysimons
10-03-16, 22:42
So, SLR and Syrac adjustable blocks fit?
This is very strange considering three different sources, including SLR and Hodge, both said that it wouldn't work.
Is that an MUR? Is it drilled for the anti-rotation pin?
Well I am leaning against saying the SLR Sentry 7 fits without clearancing because it is close enough that barrel whip and rail flex may cause the screw face to come into contact with the rail during firing. I would be curious to to get an opinion from the experts. The Syrac clears the rail no problem it seems.
What I need to find out next is how/if the MLOK slot is still functional with the gas-blocks in place.
I have a SLR GB 7 on order. I'll put it to the calipers to it and see exactly its size for comparison.
It is a MUR. Love the lines with the MEGA rail! Specifically it is the old style/Noveske variant that does not have the reduced dimensions at the front for Geissele style anti rotation tabs. It is drilled for the anti rotation pin of the MEGA/Hodge rail common to the NSR and V7WS enlightened rails. This one was cerakoted to cover Vltor's purple hued anodizing next to the perfect, deep-black MEGA anodizing.
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/D671442C-6605-477D-B7E8-5D6838DD70A6_zpsoc4nsafa.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/D671442C-6605-477D-B7E8-5D6838DD70A6_zpsoc4nsafa.jpg.html)
Well I am leaning against saying the SLR Sentry 7 fits without clearancing because it is close enough that barrel whip and rail flex may cause the screw face to come into contact with the rail during firing. I would be curious to to get an opinion from the experts. The Syrac clears the rail no problem it seems.
What I need to find out next is how/if the MLOK slot is still functional with the gas-blocks in place.
I have a SLR GB 7 on order. I'll put it to the calipers to it and see exactly its size for comparison.
It is a MUR. Love the lines with the MEGA rail! Specifically it is the old style/Noveske variant that does not have the reduced dimensions at the front for Geissele style anti rotation tabs. It is drilled for the anti rotation pin of the MEGA/Hodge rail common to the NSR and V7WS enlightened rails. This one was cerakoted to cover Vltor's purple hued anodizing next to the perfect, deep-black MEGA anodizing.
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/D671442C-6605-477D-B7E8-5D6838DD70A6_zpsoc4nsafa.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/D671442C-6605-477D-B7E8-5D6838DD70A6_zpsoc4nsafa.jpg.html)
I have an MUR on the way. I do not believe it has the anti rotation pin hole.
Is the anti rotation pin really necessary ?
jerrysimons
10-03-16, 23:10
I have an MUR on the way. I do not believe it has the anti rotation pin hole.
Is the anti rotation pin really necessary ?
I think only the Noveske varient has the anti rotation pin hole pre drilled. It was the Gen 2 upper receiver when the NSR was released. Novekse still sells them.
MEGA uppers have them. Also V Seven Weapons and Hodge Defense uppers have them.
From what I have heard. With a properly torqued and lapped barrel nut the anti rotation feature is not critical (consider the KAC URX 4 for example). It does give me a warm and fuzzy though to have the "i" dotted and "t"s crossed.
I think only the Noveske varient has the anti rotation pin hole pre drilled. It was the Gen 2 upper receiver when the NSR was released. Novekse still sells them.
MEGA uppers have them. Also V Seven Weapons and Hodge Defense uppers have them.
From what I have heard. With a properly torqued and lapped barrel nut the anti rotation feature is not critical (consider the KAC URX 4 for example). It does give me a warm and fuzzy though to have the "i" dotted and "t"s crossed.
I wonder how hard it would be to drill one myself, or have someone do it...
jerrysimons
10-03-16, 23:38
I wonder how hard it would be to drill one myself, or have someone do it...
ADCO will do it. Maybe Marvin Pitts too but ADCO lists it as a service for $50 I think with a faster turn around than Marvin probably.
ADCO will do it. Maybe Marvin Pitts too but ADCO lists it as a service for $50 I think with a faster turn around than Marvin probably.
I was thinking about Pitts. I sent him a PM on FB.
Please post pics of your upper once it's assembled.
I had a Syrac adjustable block on order, but apparently their site is down...
Does anyone have experience running a Centurion 12.5" suppressed? Is an adjustable block necessary, or is the port small enough?
I have and it was fine. CA used a small gas port, so I doubt you will have any issues.
I have the exact combination you are asking about (CA 12.5 barrel / Hodge Wedgelock 11.5 / VLTOR A5H2 with standard spring). I love it and believe you will too. I just recently replaced a NSR 11 with the Hodge 11.5. The NSR was a good rail and aside from the difficulty timing the barrel nut, I feel it is very underrated. Nevertheless, I wanted something a little stiffer and longer for IR laser and bipod use, and do not personally trust the keymod for a potentially loaded bipod. The Hodge is definitely stiffer and stronger although I still can induce some flex with very heavy 3:00 or 9:00 pressure. I have a VLTOR gas block and it fits fine. Though the Centurion gas block would provide a little more clearance, I cannot get the VLTOR block to touch the rail no matter how hard I push and I am quite large. The barrel is 4-5 years old but when I originally put it together I measured the gas port at ~.0625. Maybe it is really .065 and I made a measuring error. In any case it shoots well suppressed and unsuppressed and cycles and locks back everything I shoot. There is a small bit of gas suppressed but not enough to bother me. I do not have any desire to put an adjustable gas on there. I do have an adjustable gas block on a 10.5" barrel that was utterly obnoxious to shoot suppressed without it. Sure, you could make the 12.5" shoot a little smoother suppressed with the SLR but given how well it does without it I do not think the benefit outweighs the cost in terms of maintenance and complexity. The SLR Sentry 7 is better than the other adjustable gas blocks I have tried, but it is not bomb proof in my experience. I have had multiple (black) leaf springs lose their tension to the point where I could barely feel the detents as I turned the set screw. It is a good piece of equipment that has its place, but the cost is ongoing vigilance and periodic spring maintenance and replacement. At this point I would rather find a single gas port size and stick with it for my SBR's whether from the factory or aided by the Baby Govnah... even if that means forgetting about Tula and PMC.
Good luck.
BufordTJustice
10-05-16, 11:58
Sure, you could make the 12.5" shoot a little smoother suppressed with the SLR but given how well it does without it I do not think the benefit outweighs the cost in terms of maintenance and complexity. The SLR Sentry 7 is better than the other adjustable gas blocks I have tried, but it is not bomb proof in my experience. I have had multiple (black) leaf springs lose their tension to the point where I could barely feel the detents as I turned the set screw. It is a good piece of equipment that has its place, but the cost is ongoing vigilance and periodic spring maintenance and replacement. At this point I would rather find a single gas port size and stick with it for my SBR's whether from the factory or aided by the Baby Govnah... even if that means forgetting about Tula and PMC.
Good luck.
The purpose of an adjustable gas block isn't to manipulate the settings more than a few times, to get the gun dialed in.
ESPECIALLY on a gun that may be used for serious purposes.
I own multiple SLR blocks and have installed many on friends' guns. As long as you follow your own advice and PICK A SINGLE PORT SIZE, you'll have no issues.
You've made an apples to acorns comparison.
The purpose of an adjustable gas block isn't to manipulate the settings more than a few times, to get the gun dialed in.
ESPECIALLY on a gun that may be used for serious purposes.
I own multiple SLR blocks and have installed many on friends' guns. As long as you follow your own advice and PICK A SINGLE PORT SIZE, you'll have no issues.
You've made an apples to acorns comparison.
If you are going to pick a single gas port size and leave it alone (which I completely agree with) that begs the question of why you need an "adjustable" gas port in the first place. Why not get a barrel with an appropriately sized port (or baby Govnah) and do away with the added complexity?
If you are going to pick a single gas port size and leave it alone (which I completely agree with) that begs the question of why you need an "adjustable" gas port in the first place. Why not get a barrel with an appropriately sized port (or baby Govnah) and do away with the added complexity?
Because 99% of barrels are over-gassed. The Centurion happens to not be one of them.
A proper dedicated port is much preferred over an adjustable gas block. This barrel example can be a good choice for many.
Remember that there are many possible drawbacks of using an oversized gas port with an adjustable gas block over a base gas port that is properly sized for the use. For starters, but not limited to are the many issues of the adjustable gas blocks themselves, that could be a detailed thread on it's own. Another area to consider is that an oversized port erodes at a higher rate than a smaller port erodes, the erosion doesn't reduce if the gas is choked past that point, that's another interesting conversation.
Those are not the only two bones to toss out to chew on, just a few to think about and/or discuss before the whole skeleton get's tossed in.
BufordTJustice
10-06-16, 13:13
If you are going to pick a single gas port size and leave it alone (which I completely agree with) that begs the question of why you need an "adjustable" gas port in the first place. Why not get a barrel with an appropriately sized port (or baby Govnah) and do away with the added complexity?
Because, due to different ammo (bullet weight, powder charge, powder type, etc), temperature, suppressor characteristics, muzzled device, you may not KNOW what port size your gun requires to run optimally.
And, having used port-tune kits that fit into FSBs and LP GB's, you don't have to drop the (potentially Rocksett'ed) muzzle device and remove the gas block/FSB to make the change. Further, even A2 flash hiders have a small expansion chamber between the muzzle and the gas expansion slots. This means that it does have an effect on gas system blow-down time. So even people who are not using cans would be wise to tune their gas system with the muzzle device ON as opposed to guessing and using a bare muzzle.
Nobody is having issues with quality adjustable gas blocks "failing" in the sense that word is commonly used. They continue to function just fine. In fact, they become more fixed on a given setting the longer one uses it on that setting. And we don't consider this a PLUS?????
Get the gun dialed-in (quickly and easily, I might add), and then leave the thing alone. BOOM DONE! It's the same workflow as a dedicated port insert, but truncated (read: less work).
I have not yet heard of an SLR that "self adjusted"; much less heard of one that had done so after being set and left-alone first. I would assume the same for Syrac. The Govnah is a good product as well, but every one I have used has had slight gas leakage present around the plate aperture, not unlike every other adjustable gas block I've ever used. The gas leakage/seepage diminished greatly with time/rounds. And they are heavy AF. My Sentry 7 set screw Ti is .7oz and has HALF the coefficient of expansion of steel, so my gas seal between the block and journal gets better as I heat up the weapon (a benefit inherent to all Ti GB's, adjustable or not). The Baby Govnah is Nitrided steel and weighs between 1.2 and 1.4oz unless it is substantially different from other steel gas blocks.
The std Govnah likely doubles that to 2.8-3.0oz, assuming its made of the same steel stock. Again, not picking on anybody here, but std low-pro gas blocks are not designed to be toggled between settings. If one wants that, they'll need to pay the weight/bulk penalty of the Govnah or a Noveske Switchblock (which have had their own issues in the past). And even then, constantly screwing with gas settigns on a gun is just NOT a good idea.
Defaultmp3
10-06-16, 13:39
The std Govnah likely doubles that to 2.8-3.0oz, assuming its made of the same steel stock.Heh, it's worse than you thought, as the standard Govnah's weight is published to be 4.1 oz.
BufordTJustice
10-06-16, 14:33
Heh, it's worse than you thought, as the standard Govnah's weight is published to be 4.1 oz.
Still lighter than a forged FSB, but not by much. That's what is required if one wants to repeatedly jack with their gas settings. I choose to shave the 3oz+ and basically get my light and mount for nearly "free", in weight terms (Inforce WML)
jerrysimons
10-06-16, 14:37
I have heard of Syrac internal detent springs seized due to fouling in the depressed position leaving the screw to spin freely. Now the screw would likely also be seized due to fouling, so the GB would, for the most part, be left in the last position. BUT the screw could spin if knocked around. No doubt that adjustable gas blocks introduce components that can fail and deadline a gun. SLR Rifleworks has the most robust design. I highly doubt their revised leaf spring would ever weaken enough due to heat to fail to act as a detent, the notches in the screw that the detent fits into are deep and the leaf spring material very stout. Now maybe the leaf spring screw works loose but that thing is in their tight. I stopped trying to remove one once because I was at the point of stripping my allen wrench. So if the SLR Sentry adjustment screw seized due to fouling it is stuck in the last left position. If this happened in a critical situation, hopefully, during tuning, you left some margin in the adjustment for function and did not just leave it on the ragged edge. This also means tuning for lowest common denominator, which for some is crap ammo, but probably the most realistic over looked factor is Weather! Freezing temperatures are not fun to go to the range in, but if you might need your gun outside during winter, you better make sure your GB adjustments can accommodate the drop in pressure from cold ammo/gun.
The same idea applies to a BRT gas block insert. Though I might favor slightly more margin of gas flow (read slightly bigger port) for a mostly permanent solution. Clint has the port size stuff figured out! He can tell based on your setup exactly what size would cut down on over-gassing and still function well based on ammo and setup. It is not going to be on the ragged edge but will not be overgassed either.
Tom12.7, as always, has some good points in favor of barrel port size over adjustable gas blocks but unfortunately conservatively ported barrels are the hardest thing to find. Some of the the points he made, like increased port erosion due to large a gas-port opening inside a barrel, apply equally to both the AdjGB and the BRT GB insert.
I think the BRT insert would be more robust long term than the Baby Govnah's simple drilled hole, but both regulate the same way, and the BRT insert can be installed in any GB.
At this point I am leaning heavily toward the BRT gas block insert inside the recommended SLR Rifleworks GB7 for my 9.31" MEGA Wedge Lock rail and 10.5" carbine gas Novekse barrel. Problem is the Syrac Gen 2 was pinned at the factory and the GB7's slender design requires pinning (only one set screw). I don't think the barrel can (should) be pinned again or the gas block lined up perfectly enough when drilling to use the existing pin channel. So...?
Anyway, back to gas block compatibility:
The first MLOK slots on the end of the 9.3" rail are directly over the carbine length gas block placement. The size of the Syrac Gen 2 gas block, even though it clears the rail internally enough for use, renders some of the MLOK slots unusable. I only checked MLOK function with the Syrac Gen 2 because it cleared better under the rail then the SLR Sentry 7 did (see pics above). The SLR Sentry 7 adjustable would likely be worse since it didn't clear as well. I used Arisaka Defense MLOK attachments because they rock!
Pics:
10:30 clears
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/88767361-7BF9-4D1E-9326-6C61CC8B57C9_zpsp1ldbhrn.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/88767361-7BF9-4D1E-9326-6C61CC8B57C9_zpsp1ldbhrn.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/EE69920D-7AD6-49CA-A590-D5EAF6E46459_zpsjh51fqh3.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/EE69920D-7AD6-49CA-A590-D5EAF6E46459_zpsjh51fqh3.jpg.html)
9:00 clears but it is close, screws might need to be shortened
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/EE1AF4CC-7D7C-408B-853C-90D07509F018_zpsgu6lph4q.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/EE1AF4CC-7D7C-408B-853C-90D07509F018_zpsgu6lph4q.jpg.html)
6:00 does not clear anything not even a Magpul MLOK panel
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/0741DD1D-7F98-4D18-A40C-B8DC108EFB4B_zpsn7zmexdo.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/0741DD1D-7F98-4D18-A40C-B8DC108EFB4B_zpsn7zmexdo.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/89E27096-863A-413E-9398-C8C1E7B16024_zpst1drcxhu.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/89E27096-863A-413E-9398-C8C1E7B16024_zpst1drcxhu.jpg.html)
3:00 does not clear, not with out cuting the screws down a little that is. The upper is only mocked up. The barrel might be leaning a little or the outer dimension of the GB are not concentric with the inner (read thicker on one side).
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/B20457C5-5475-4B41-9AAD-F50C1BE2DC80_zpsripd2tig.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/B20457C5-5475-4B41-9AAD-F50C1BE2DC80_zpsripd2tig.jpg.html)
1:30 clears
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/A42B84CC-5CCC-4497-B126-14005D76E4D0_zpshxczhvr8.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/A42B84CC-5CCC-4497-B126-14005D76E4D0_zpshxczhvr8.jpg.html)
http://i8.photobucket.com/albums/a24/accidentprone86/Mobile%20Uploads/B47ECC5A-0403-49B2-9BA4-D9BCFF553151_zpsoylknpkd.jpg (http://s8.photobucket.com/user/accidentprone86/media/Mobile%20Uploads/B47ECC5A-0403-49B2-9BA4-D9BCFF553151_zpsoylknpkd.jpg.html)
This damn rail is thin! In the pic with my KAC CQB showing the over hang of the Arisaka Defense inline ring mount past the rail, well the part over hanging on the light mount is actually below the outer diameter of the silencer! Good thing there is a little gap between the end of barrel and the end of rail. The Hodge Defense 10.75" rail with a 11.5" barrel might have some issues here depending on the "[non]issued" silencer and the particular attachment.
I have a SLR GB7 gasblock coming. I will do further testing to see if the GB7 gasblock will work better underneath the MLOK slots. The 6 o'clock was really tight with the Syrac the GB7 is going to have to be real short to work!
jerrysimons
10-06-16, 15:27
I have the exact combination you are asking about (CA 12.5 barrel / Hodge Wedgelock 11.5 / VLTOR A5H2 with standard spring). I love it and believe you will too. I just recently replaced a NSR 11 with the Hodge 11.5. The NSR was a good rail and aside from the difficulty timing the barrel nut, I feel it is very underrated. Nevertheless, I wanted something a little stiffer and longer for IR laser and bipod use, and do not personally trust the keymod for a potentially loaded bipod. The Hodge is definitely stiffer and stronger although I still can induce some flex with very heavy 3:00 or 9:00 pressure. I have a VLTOR gas block and it fits fine. Though the Centurion gas block would provide a little more clearance, I cannot get the VLTOR block to touch the rail no matter how hard I push and I am quite large. The barrel is 4-5 years old but when I originally put it together I measured the gas port at ~.0625. Maybe it is really .065 and I made a measuring error. In any case it shoots well suppressed and unsuppressed and cycles and locks back everything I shoot. There is a small bit of gas suppressed but not enough to bother me. I do not have any desire to put an adjustable gas on there. I do have an adjustable gas block on a 10.5" barrel that was utterly obnoxious to shoot suppressed without it. Sure, you could make the 12.5" shoot a little smoother suppressed with the SLR but given how well it does without it I do not think the benefit outweighs the cost in terms of maintenance and complexity. The SLR Sentry 7 is better than the other adjustable gas blocks I have tried, but it is not bomb proof in my experience. I have had multiple (black) leaf springs lose their tension to the point where I could barely feel the detents as I turned the set screw. It is a good piece of equipment that has its place, but the cost is ongoing vigilance and periodic spring maintenance and replacement. At this point I would rather find a single gas port size and stick with it for my SBR's whether from the factory or aided by the Baby Govnah... even if that means forgetting about Tula and PMC.
Good luck.
Have/Can you check the function of the MLOK slots at the gas block location? Do the t nut screws clear your Vltor gas block?
A proper dedicated port is much preferred over an adjustable gas block. This barrel example can be a good choice for many.
Remember that there are many possible drawbacks of using an oversized gas port with an adjustable gas block over a base gas port that is properly sized for the use. For starters, but not limited to are the many issues of the adjustable gas blocks themselves, that could be a detailed thread on it's own. Another area to consider is that an oversized port erodes at a higher rate than a smaller port erodes, the erosion doesn't reduce if the gas is choked past that point, that's another interesting conversation.
Those are not the only two bones to toss out to chew on, just a few to think about and/or discuss before the whole skeleton get's tossed in.
Toss it in Tom;) Let's hear it
Let's start simple at first and work our way from there.
First we might want to ask the question of what components receive the erosion? For a properly ported barrel with normal pinned FSB, that is mostly the barrel, with some in the gas block and tube, and a more minor amount in the key. For an oversized port in the barrel with an adjustable gas block, you will get more aggressive barrel port erosion with more erosion in the gas block at the orifice and vector changes (not talking about the 90 degree turn for the tube), with some in the gas tube, and a more minor amount in the key. That does change the quantity of gas flow with use.
We may want to ask the question about why those may be more durable in a lifespan of each other in a comparison? Lets look at the regular forged pinned FSB vs a possible adjustable one. Which ones has more possible parts to fail? Which one has components that may be subject to more erosion? Which of those has the orifice wire drawn in a direction that makes future adjustments impractical due to the mass subjected being reduced in the wire drawn locations that are directional? The adjustment doesn't carry the thermal input capacity of the barrel, the mass isn't there and it can not conduct it away fast enough to transfer it.
Let's start here and work our way out from the basics.
If we are given 2 systems that are identical except for two items, one with a proper port and a normal pinned gas block, the other with an oversized port an adjustable gas block. If both had identical schedules of use, do you think that one may tend to do better than the other for use?
BufordTJustice
10-06-16, 20:57
Let's start simple at first and work our way from there.
First we might want to ask the question of what components receive the erosion? For a properly ported barrel with normal pinned FSB, that is mostly the barrel, with some in the gas block and tube, and a more minor amount in the key. For an oversized port in the barrel with an adjustable gas block, you will get more aggressive barrel port erosion with more erosion in the gas block at the orifice and vector changes (not talking about the 90 degree turn for the tube), with some in the gas tube, and a more minor amount in the key. That does change the quantity of gas flow with use.
We may want to ask the question about why those may be more durable in a lifespan of each other in a comparison? Lets look at the regular forged pinned FSB vs a possible adjustable one. Which ones has more possible parts to fail? Which one has components that may be subject to more erosion? Which of those has the orifice wire drawn in a direction that makes future adjustments impractical due to the mass subjected being reduced in the wire drawn locations that are directional? The adjustment doesn't carry the thermal input capacity of the barrel, the mass isn't there and it can not conduct it away fast enough to transfer it.
Let's start here and work our way out from the basics.
If we are given 2 systems that are identical except for two items, one with a proper port and a normal pinned gas block, the other with an oversized port an adjustable gas block. If both had identical schedules of use, do you think that one may tend to do better than the other for use?
Which is exactly why i use and advocate for a slightly undersized gas port along with an AGB.
And, firing schedule is going to have an enormous bearing on the rate and place of erosion within the gas system.
While we are talking of Centurion Barrels and Syrac AGBs, can anyone point my to a Sycrac AGB for sale in the .750 set screw variety? Their site is down and my message went unanswered. I have the barrel, need the block.
jerrysimons
10-06-16, 21:52
No doubt for military firing schedules and solider proofing an adjustable gas block, even SLR's, is out of the question. I am not against them though for personal use on a serious gun. I think the SLR Sentry 7, as BufordTJustice attests, is up to the task for a personally owned and maintained duty rifle or home defense gun. Certainly though it is another component, and one critical, that can wear and break. For most users with most barrels it can be a great option, even if not the most long term durable set up in extreme conditions/circumstances. The benefits it offers in readily correcting most (Tom points out some it does not) issues of function and durability (excessive bolt wear, extraction issues, gas to face, recoil) associated with an over gassed barrel are worth it. For a bomb proof gun or go to war gun or SHTF gun maybe one wants to select a properly ported barrel or, as I am leaning toward, gas block inserts. Inserts won't do anything internal barrel gas port erosion but certainly they are a more long term robust and mistake proof option over even a SLR Sentry ADJ GB.
While we are talking of Centurion Barrels and Syrac AGBs, can anyone point my to a Sycrac AGB for sale in the .750 set screw variety? Their site is down and my message went unanswered. I have the barrel, need the block.
SLR > Syrac. All day. I am holding of on saying that the Syrac fully compatible under the Wedge Lock rails until I can compare it to the recommended GB7.
SLR > Syrac. All day. I am holding of on saying that the Syrac fully compatible under the Wedge Lock rails until I can compare it to the recommended GB7.
Please elaborate.
I have read just the opposite.
jerrysimons
10-07-16, 06:02
Please elaborate.
I have read just the opposite.
Sorry I could have been more clear. I do not favor or recommend the Syrac design over the SLR generally, so much so that I bought a SLR anyway even though my barrel came with a Syrac pinned to it. I did not know if the poster I was replying to planned on using the Wedge lock rail or not, if so it seems he is stuck with the Syrac as the only option (maybe others out there but if they don't have a detent I don't even look). I passed along some misinformation in my first post. I want to avoid that and at this point I will not outright say the Syrac adj gas block is fully compatible with the Wedge Lock rails. I plan to get to the bottom of the issue, but I can't until I have the recommended GB7 as a baseline. In the meantime I hope to document enough information that people can make up their own mind. The fit between the MLOK t nut screws and the gas block on the 3 and 9 o'clock is troubling to me. I would like to see more clearance without having to shave down anything.
I have never read anything on this forum I don't think that wasn't SLR over Syrac.
Sent from my iPhone using Tapatalk
BufordTJustice
10-07-16, 09:48
No doubt for military firing schedules and solider proofing an adjustable gas block, even SLR's, is out of the question. I am not against them though for personal use on a serious gun. I think the SLR Sentry 7, as BufordTJustice attests, is up to the task for a personally owned and maintained duty rifle or home defense gun. Certainly though it is another component, and one critical, that can wear and break. For most users with most barrels it can be a great option, even if not the most long term durable set up in extreme conditions/circumstances. The benefits it offers in readily correcting most (Tom points out some it does not) issues of function and durability (excessive bolt wear, extraction issues, gas to face, recoil) associated with an over gassed barrel are worth it. For a bomb proof gun or go to war gun or SHTF gun maybe one wants to select a properly ported barrel or, as I am leaning toward, gas block inserts. Inserts won't do anything internal barrel gas port erosion but certainly they are a more long term robust and mistake proof option over even a SLR Sentry ADJ GB.
SLR > Syrac. All day. I am holding of on saying that the Syrac fully compatible under the Wedge Lock rails until I can compare it to the recommended GB7.
As Tom rightly noted, the original gas port size has a large effect on the toughness and longevity of an adjustable gas device.
I use a Faxon 18" gunner (rifle gas with a .081" GP) for my patrol rifle and a Sionics 11.5" RGP barrel for my two stamper SD/HD, until a skunk works 16" intermediate gas, reduced/optimized gas port, taper profile barrel is released by one of our members. [emoji12]
That will likely be my new patrol upper and relegate my Faxon to range fun unless my wife steals it for herself.
But, Tom is right; start with a correct gas port, or even a slightly small one and you're ahead of the game.
jerrysimons
10-07-16, 10:01
http://www.blackrivertactical.com/store.html#!/BRT-16-OPTIMUM-Series-Barrel/p/61518552/category=1852006
Boom.
http://www.blackrivertactical.com/store.html#!/BRT-16-OPTIMUM-Series-Barrel/p/61518552/category=1852006
Boom.
Interesting.
BufordTJustice
10-07-16, 10:35
http://www.blackrivertactical.com/store.html#!/BRT-16-OPTIMUM-Series-Barrel/p/61518552/category=1852006
Boom.
That's the one. ;)
I spoke with Clint about it before; the gas tube length is bespoke, but he sells them for $10 each..... And you KNOW they're quality.
And, it's bespoke because a lot of design work was done to optimize dwell time, gas port location, and gas port size.
Clint is building quite a stock of gas tubes, so supply is a non issue.
Been following this thread closely and a few thoughts come to mind.
It seems obvious that having the correct port size from the start is ideal.
From the consumer side, we would benefit from manufacturers fine tuning more barrels and then publishing the ammo and buffer system that works with it, from quality plinking to premium grades, to buffer weights and carbine/A5 systems, using standard M16 BCG.
No doubt much of this is known already by the manufacturer in their testing.
What keeps manufacturers from doing this? I've seen some mention their test ammo in passing but nothing to help the average consumer build a well tuned system.
Or maybe they just open the poor for the crappiest ammo because over gases guns don't receive customer service complaints.
BufordTJustice
10-07-16, 12:54
Been following this thread closely and a few thoughts come to mind.
It seems obvious that having the correct port size from the start is ideal.
From the consumer side, we would benefit from manufacturers fine tuning more barrels and then publishing the ammo and buffer system that works with it, from quality plinking to premium grades, to buffer weights and carbine/A5 systems, using standard M16 BCG.
No doubt much of this is known already by the manufacturer in their testing.
What keeps manufacturers from doing this? I've seen some mention their test ammo in passing but nothing to help the average consumer build a well tuned system.
Or maybe they just open the poor for the crappiest ammo because over gases guns don't receive customer service complaints.
A large part of the equation is the lowest common denominator; the uninformed consumer.
This mouth breathing piece of shit will run his gun bone dry with tula while bump firing over the berm. And the SECOND he encounters a malfunction (a "jam"), he'll blame the gun and post pictures all over the internet, omitting any exculpatory evidence that it may have been the idiot user or his shit ammo.
And then it becomes internet Canon.
This can be addressed by active comms on forums, user education, etc. But it'll never be fixed until the users educate themselves. Akin to not changing the oil in a car, it's THAT KIND OF DUMB.
Add to that a lack of proper tolerances and trueness between the barrel, barrel extension, receiver, and receiver extension, improper surface finishes, burrs, etc... And there cab be extra friction created by a lack of quality manufacture and assembly.
FWIW, I believe this adjustable block is compatible with the Wedge Lock:
http://www.nitactical.com/product/adjustable-titanium-gas-block-black/
Furbyballer
11-01-16, 06:25
FWIW, I believe this adjustable block is compatible with the Wedge Lock:
http://www.nitactical.com/product/adjustable-titanium-gas-block-black/
Never heard of these guys before. Are you basing that off the published dimensions?
jerrysimons
11-01-16, 09:25
Never heard of these guys before. Are you basing that off the published dimensions?
NSZ85 put one under a Mega rail in his install video, no comment on fitment or MLOK function
https://www.youtube.com/watch?v=hPIDoQ1ELHw
It seems to fit inside the rail but I would bet the MLOK slot on the 3 or 9 o’clock side is unusable based on the lope-sided shape of the gas-block.
My pedantic tome on the topic:
https://www.m4carbine.net/showthread.php?189879-MEGA-ARMS-Hodge-Defense-Systems-Wedge-Lock-rail-gas-block-and-MLOK-compatibility
My pedantic tome on the topic:
https://www.m4carbine.net/showthread.php?189879-MEGA-ARMS-Hodge-Defense-Systems-Wedge-Lock-rail-gas-block-and-MLOK-compatibility
Nice! I must have missed this during my recent travels.
It looks like the MLOK slots would not be usable with the aforementioned GB. Apologies.
jerrysimons
11-01-16, 14:39
Nice! I must have missed this during my recent travels.
It looks like the MLOK slots would not be usable with the aforementioned GB. Apologies.
Probably not an issue on your carbine gas 12.5"/ 11.5" rail combo. The affected slot would be further back toward the seldom for mounting area.
Probably not an issue on your carbine gas 12.5"/ 11.5" rail combo. The affected slot would be further back toward the seldom for mounting area.
Yep. I was thinking the same.
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