View Full Version : To FSB or Not FSB?
Hey everyone. I'm in the middle of purchasing my first AR and I'm having a hard time deciding on wether or not I want a fixed front sight or not. I plan on purchasing one of BCM's BFH 14.5 middies and running an Aimpoint T-1 with a folding rear sight. I don't care much for fixed rear sights when running optics. I'm having a hard time deciding between a 9in rail and a fixed sight or a 12in rail and using a folding sight.
Are there any advantages or disadvantages to each besides personal preference? Thanks in advance.
(sorry if this is a noob question, I tried searching but couldn't find much on the specific topic of FSB or not)
Oh yeah, happy turkey day.
Rationally speaking, FSBs are the way to go but, this of course, highly depends on what you really need.
Think of the following:
-how far forward do you grip your fore end?
-what position do you run your light?
-co-witness if "obstruction" matters to you...
...And whatever else applies to your weapon.
I, for instance, dont grip past 9.5" with my thumb at 12 o'clock, run a G2 at 3 o'clock-activating it with my middle finger from underneath and run a T-1 on lower 1/3 co-witness mount so 9in rail works just fine for me.
Is this your first AR? I ask because that's a set up that I've found works well for me, hence, I'm pretty comfortable limiting myself that way. If you're still figuring that out, it might be wiser not to "commit" to a rail just yet... Instead, opt for a basic FSB upper and run a MOE in the meantime, until you find what config works for you. Secondly, if this is a first AR, a 16 middy would be the way to go so as not to limit yourself with the bigger commitment of a pinned muzzle device which you may later find out doesn't work for you. Just my .02.
In some previous post, someone mentioned that a FSB can be used for a backup sight at close range, even without the rear BUIS up, should the Aimpoint fail.
Also, I understand the FSB is more durable than a front folding sight.
Inkslinger
11-24-11, 19:20
In some previous post, someone mentioned that a FSB can be used for a backup sight at close range, even without the rear BUIS up, should the Aimpoint fail.
Also, I understand the FSB is more durable than a front folding sight.
Correct on both. A standard FSB is definitely more hearty than most folding sights. Plus your optic can essentially become a very large aperture sight if your batteries shit bed. Some guys won't even consider putting a rail mounted sight on a fighting rifle for these very reasons.
Thanks for the responses.
I don't grip very far, I have shorter arms and I don't like feeling like my arm is 'stretched out'.
I plan on using a Surefire G2 at 2 'o clock and activating with my thumb (I'm a lefty). Also, using a tango down shorty as a hand stop.
I've had the opportunity to shoot a few AR's owned by friends and I've come to prefer the TD shorty over a hand stop, like the KAC one. Plus it can hold batteries.
I think I'm going to go with the fixed sight. When I think about it, I just don't think I'd use the extra rail length.
As far as muzzle device, I plan on running a BC 1.5. I've shot with one once and I definitely liked it.
I like a Daniel Defense or LMT fixed front on a rail because I like to have an X300 right in front of it. I don't use a VFG and I like to shoot off of both shoulders.
I have a folding front sight on my 6940 which I like for using optics, but it is a folding sight and needs to be flipped up to use, costing an extra second if your optic died mid battle. Of course if you have an aimpoint that might never happen lol. Also the front sight could be knocked down accidentally. Just things to think about. However, I do like the uninstructed view though optics with the folding front sight.
For me a real, pinned, forged steel FSB is mandatory on a fighting gun.
Nothing folding ever would be found on any gun I own... EVER.
Come on Mark not even one of those wicked cool UTG folding VFG's?:rolleyes:
I agree with MarkM a fixed font sight is my choice but this is your gun. I choose the fixed FS because it is rugged, simple and has less to go wrong with it. It is also cheaper. I like DD, LMT and Larue fixed rear sights too.
Come on Mark not even one of those wicked cool UTG folding VFG's?:rolleyes:
Yeah! I run those... I meant folding sights. :cool:
acaixguard
11-25-11, 09:42
I run the DD fixed front site. Not quite the same as a real pinned FSB, but the next best option?
I run the DD fixed front site. Not quite the same as a real pinned FSB, but the next best option?
I'm running one of those too. Not too bad. The site picture is flawless, but it looks to be an extruded alloy base.
Coming from a similar spot where the OP did months back, I thought the front sight block would get in the way.
However everything I read said always run with your BUIS up and fixed sights are better than folding sights (more robust that is), so on my rifle I did a DD 1.5 rear with a standard fixed front sight/MOE upper. You will be surprised at how "invisible" that front sight is with an optic/RDS. I run a micro aimpoint (lower 1/3 co-witness) and I don't see the front sight post at all. I don't see the rear sight either. Both are fixed.
Get the fixed front sight. Its not as bad as you think.
Later you may determine that your application may require something different. Use that as an excuse to buy another rifle :D
For me a real, pinned, forged steel FSB is mandatory on a fighting gun.
Nothing folding ever would be found on any gun I own... EVER.
Why is that?
ETA: I run all rail mounted front sights, mostly fixed. They are all up and ready to go. I agree that if there is an optic the irons should still be up.
I really think its personal preference. I always find fixed front sights to annoy and distract me... I think it's because of all my military training with only iron sights, I find myself naturally drawn to the front sight even with RDS active.
ForTehNguyen
11-25-11, 12:50
its personal preference if you want to have the FSB in the view of your optics. I want a 100% clear picture so I run flips on my 12" DD rail upper with an eotech
Another thing I've noticed about FSB + handguard setups vs flip sights on rail setups is that FSB arent as light as you would think. The FSB alone weighs about 5oz, then the delta ring and handguard cap are another few oz (of which a railed system doesnt have). I've seen some middy FSB + handguard setups weigh very close to some middy + 12" rail setups.
I dont think thats its a personal choice at all. Its a profesonial choice. Everything else is secondary to the FSB. They will all break, shift or fall off before the pinned FSB.
Why is that?
Folding = breakage point.
I don't think the 6940 front sight is going anywhere. It's pinned and forged on but still folding. A good quality rear folder like a
Troy isnt going to break very easily either.
Still, fixed and FSB seems the toughest possible.
I think I would feel comfortable with no FSP if it were something as solid as the DD Lite rail with a DD fixed front. This would allow you to place your sight anywhere and also your hands. But... its a pricey rail. The new DD tube rail looks very solid also, but the Lite just looks so rock solid.
Folding = breakage point.
Agree. The alternative being a rail mount fixed sight with a pinned gas block. Protects the gas block even better.
OP, you're getting some good input. Mine, recently, was partly good and partly not. One guy claimed the question was "silly:" https://www.m4carbine.net/showthread.php?p=1143835#post1143835
Many feasible mounting solutions for lights with a FSB
http://i163.photobucket.com/albums/t294/myersma2/a11b62c6.jpg
http://i163.photobucket.com/albums/t294/myersma2/9b7601b8.jpg
I think if you stick with an FSB your options are either the IWC light mounts or a FSP rail, both of which keep the light off of the FSB.
http://www.impactweaponscomponents.com/product/tmc-1-light-mount-n-slot/
http://www.impactweaponscomponents.com/product/smc-light-mount-1-00/
http://www.impactweaponscomponents.com/product/tmc-1913-picatinny-light-mount-n-slot/
Nothing wrong with mounting on the FSB though...I love where it puts the light on my 12"
http://i163.photobucket.com/albums/t294/myersma2/3381ba7a.jpg
jonbondave
11-25-11, 18:54
If the FSB bugs you in your sight picture, you can buy a riser for your optic that'll place your irons in the bottom 1.3 of the glass, I think this is a good option. I like a standard FSB personally and usea LaRue BUIS.
Fixed. Same reasons basically as markm. Try as I do to prevent it, my guns get banged around.
With the strength, quality and durability of current optics I really don't see that you need a fixed FSB. A good quality set of back up sights are all I feel I need on my ARs.
I run long free float rails that cover the gas block and Troy flip up sights. Couple with good quality primary optics I have no problem with this setup.
Cameron
mass-diver
11-25-11, 21:19
With the strength, quality and durability of current optics I really don't see that you need a fixed FSB. A good quality set of back up sights are all I feel I need on my ARs.
I run long free float rails that cover the gas block and Troy flip up sights. Couple with good quality primary optics I have no problem with this setup.
Cameron
That's how I feel - high quality optic with high quality flip-ups is worth a very slight trade off in durability for a much better FOV IMHO.
Tim McBride
11-25-11, 21:26
I prefer a fixed FSB, with a cut carry handle rear sight, and bottom 1/3 co witness on my optic.
Nothing to break on the iron sights that way and they are there if I need them with no fooling around.
With the strength, quality and durability of current optics I really don't see that you need a fixed FSB. A good quality set of back up sights are all I feel I need on my AR's.
Cameron
I understand this viewpoint. I have never had an issue with my Aimpoints. I guess I just look at running a FSB as a way to decrease the probability of an issue. Mr. Murphy comes knockin' at the worst times.
I think both setups can be valid, given particular circumstances.. though I far prefer fixed FSB's. Tougher and easier all around.
Many feasible mounting solutions for lights with a FSB
I run basically the same setup but with a 6P
http://img.photobucket.com/albums/v11/DavePAL84/random/FSB01.jpg
FSB all the way. The only viable reason why I would not have one mounted on my rifle is if I am running magnification and want a very clear field of view.
FSB all the way. The only viable reason why I would not have one mounted on my rifle is if I am running magnification and want a very clear field of view.
Yeah but anything over 4x it doesn't matter as much. Running a variable, I could see it. Even still, I just prefer a riser in lieu of no FSB but not everyone is okay with that.
For the record, my DMR-ish gun has a folding front sight (and the only AR I own that has one)
I run scopes, rds, whatever. I like the weapon to have all the flexability I can have. So...
Now I run all troy f/u. I feel its "right" for me.
But if you plan to beat the shit out of your weapon, go fsb and handle rear or cut. It takes the bs factor down a few pegs.
That said , never had a problem with flipups.
GeorgiaBoy
11-25-11, 23:47
All of my guns have fixed FSB's. Thats not to say that I wouldnt run a railmounted FSB, and my next build probably will have one.
For my purposes, my guns are HD/SD and competition guns, so worrying about FSB's getting damaged isn't a big deal for me.
Meta-Prometheus
11-28-11, 15:34
I personally like having the FSB on my AR's. Of course I have only run irons on mine. The only time I would have rail mounted flip up sights for an AR is if I was going to run a magnified scope.
FSB for irons or RDS optics. Flip-Up/rail mounted for magnified scopes.
Just my 2 cents.
high quality optic with high quality flip-ups is worth a very slight trade off in durability for a much better FOV IMHO.
I disagree with "very slight tradeoff". Give me a rock and we'll see how long those 12" free float rails with rail mounted front sights last, compared to a rock vs. an A2 FSB.
As for "much better FOV", if you're shooting a red dot like you should - both eyes open - the FSB doesn't obstruct anything. If the red dot is properly mounted - lower 1/3 cowitness height - even with support eye closed the FSB still isn't a visual obstruction.
I try and use mostly iron sights, but I have two AR's with optics (not counting optic-equipped M4 I carry at work). One is an LMT 10.5" with A2 FSB, Troy rear folding sight, and an Aimpoint T-1 in LT660 mount. The FSB doesn't get in the way. Ever. I wouldn't dream about removing it and putting on a different gas block. The other is a 16" BCM midlength with fixed FSB and TA31F ACOG. Again, the FSB doesn't get in the way, as it is only a slight blur at the ACOG's 4x magnification. Thousands upon thousands of M4's in the military are set up similarly (ACOG w/ FSB).
The only time I could see a legitimate use for getting the FSB out of the way is 1-4x scope or something similar. The FSB is distracting on all but near 4x.
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