Ok guys, I understand the gas block is less than ideal as a front sight mounting location, but is there a solution that is at least remotely feasible?
I have normal 2 piece standard hand guards on my rifle (armalite… I know… it’s already got a BCM bcg and charging handle, been working on other reliability improvements, it’s been good to me so far), and no real desire to hang a quad rail etc on the gun, just not anything I need.
I would like to have a reliable backup sight solution though, and the only rail on my gun other than the receiver is the front gas block. I have an EOtech 512 as primary, I like the FOV etc, and I am comfortable with it. Just need a SHTF backup solution.
Most railed gas blocks have their picatinny rail at a lower plane than your upper receiver. Not every manufacturer makes a front sight that will accommodate this. Troy does, but it IS a different model than their normal front sight and is noticeably taller.
S&W railed gas blocks are receiver height, but most other companies use the lower-plane railed gas blocks, which I ASSume Armalite also uses. You’ll want to find out for sure though.
And I know this next part isn’t what you’re lookin for, but in my experience its simpler to sell that upper and get one setup the way you’re looking for. Railed gas blocks with flip sights (that almos always have to be mounted backwards to fold flat) are a pain in the ass.
All great choices… NO Magpul or other “plastic” sights.
my buddy bought a S&W o.p. and learned that the tough way.
I’m a fan of the Troy but it’s going to be your sight and then sometimes come downs to what’s the best deal you can find at the time your looking.
It is pretty easy to find out if you have a same plane gas block. Also, why would he sell the upper just because of the gas block lol. This isnt tos, most here are capable of swapping a gas block, or, shipping it out to have it done. And lol on the flip gas block comment. I’ve yet to see someone mount one backwards.
Imo just use a standard fsb and use it as a co witness. Best way to go bar none. Many on here with scopes, dots, etc use em with no issue what so ever. Best way to go bar none.
Actually, putting the front sight on the gas block is preferred – your pointer is actually on the “Bullet hose” itself as opposed to a plane that ain’t moving (while the barrel whips and vibrates like a tuning fork).
I just got home and haven’t checked to see if the gas block was on a different plane (physically lower) than the receiver. If the GB is lower, what would be an ideal rear sight setup to compensate?
It seems like in a perfect world the GB would be ideal, I definitely searched around, I’ve seen opinions both ways. I am just trying to find an ideal solution.
Thank you for the input so far guys, I definitely do appreciate it.
I dont know of a valid way to compensate for the lower gas block height by means of the rear sight. I have an upper with a railed gas block that sits lower than the receiver rail. I have the Troy gas block folding sight and I havent had a problem with it. I dont have it mounted backwards and it folds down perfectly with standard handguards and Magpul handguards. A bonus is that it has a qd sling swivel slot on each side, although I cannot attest to their true functionality because I have never attached my sling to the sight other than test fitting.
Preferred for what? It only whips and vibrates after I’ve fired… and I don’t really need the iron sights at that moment. Besides, most people run back up irons, with an optic primary…rendering this irrelevant.
Any perceived accuracy gain is completely offset by gas block rails sucking at everything.
You just want a standard rear sight. It’s the front sight that compensates for the drop in height. If you gas block is same plane, then you get a standard sight. If your gas block is lower, then get a “gas block” height sight.
My statement comes from experience (not “I read online…”) with uppers like the OP describes, and the ‘solution’ is rarely ideal and almost always a compromise from what the user is really looking for. The OP sounds like a more beginner user, thus the whole point of the thread / question, and the recommendation of what I would do (sell the upper, as it’s not worth spending the money on having a shop install a fixed A2 FSB or similar). You often spend less money selling the complete upper and buying what your really want (which might be the situation of the OP…or might not, additional variables must be decided by him). Installing a fixed A2 FSB isn’t cheap or easy, as you recommend (which I agree with, I like the fixed A2 FSB and almost universally despise railed gas blocks). Lower-height railed gas blocks are silly and are simply a cost-saving measure. Nothing more.
You’re absolutely right about many users here being capable of adjusting rifles to their needs…however, not all users here are as capable. There’s a reason he posted the question: he’s not likely among that group (…hence the post).
Lower height railed gas blocks, coupled with most handguards, often cause interference issues with that require the need for reversing the folding front sight (in order to fold/lock flat). The longer post of the gasblock-height folding sight causes problems with laying flat when installed correctly (they will not fold flat, they interfere with the handguard). Subsequently, many users turn the front sight around so it folds flat (folding forward). If you have yet to see it, then keep looking. It’s fairly common with those.
So, like I said in my previous post, it generally involves more money (in my opinion), and most people should just get the setup they want in the first place.
This isn’t the case with ALL handguards and gas blocks out there, but it is with many.
the ADVANTAGE of gas block sights is that they move with the barrel as it flexes from heat, pressure, whatever…
your rifle will be MORE consistently accurate with gb sight than forearm sight.
DO consider, “Most railed gas blocks have their picatinny rail at a lower plane than your upper receiver” - you will need to use a “gas block height” sight.
i have a few AR’s, one of which is an RRA varmint with railed gas block.
guess what? it shoots GREAT with a YHM gb-height front sight.
esp since you’re just looking for a BUIS, find something you think is cool and get it.
(but…advice from a (real) SEAL: leave your buis UP at all times.)
as to armalite, you’ve already done most of what you need to do by getting a bcm bcg. keep your gun wet and play with your buffer weight to match your loads.
since you’re just looking for a BUIS, find something you think is cool and get it.
There’s no worse criteria than what one “thinks is cool.”
(but…advice from a (real) SEAL: leave your buis UP at all times.)
Why buy a flip up sight if you plan to always leave it up? I do agree on keeping BUIS deployed always, but prefer fixed sights to reduce complexity and eliminate the risk of them being accidentally folded down.
I should preface this with the fact that I am not a smith…no expert. But…I have an A4 FSB that mounts on a railed gas block that I wouldn’t mind selling if you can’t find one. It came mounted an an SR-25 I purchased years ago that was a lightweight Match RAS version dressed up in standard A2 fashion. I believe KAC used to sell setups like this. I’m not sure if the fact that is was meant to be used with the larger carry handle sight would matter…perhaps someone here who knows more than I would know.
