AR front sight confusion and an odd request...

[Shifty]

So my front sight on my new (and only) AR-15 rifle is causing me some concern. Its a 2012 mfg Olympic Arms 6.8 SPCII flat top, 16" carbine with a fixed front sight.
From my limited research, it is my understanding that the front sight base should be an "F" marked type. However there are no markings at all except a "2" on the left side, which I understand to be a forge mark, and the word "up" behind the sight but no corresponding arrow to indicate direction of turn.
Also, it has a 5 prong adjustment on the front post, and my AR front sight tool does not fit....... do I have an A1 sight? Why would they put a non F marked FSB with an A1 post on a new mfg rifle? very confused

My request... Show me your fixed front sights, including the post, and describe what type they are and what you use for a rear sight. Also if you have any issues achieving zero

 

[Shifty]

also, I have almost no experience with this rifle type, so If any of you think that front sight post looks unusual, let me know. it looks rough, and more open / cut-away, than the others I have seen. Your thoughts and opinions are welcomed

 

[briansmithwins]

If the front sight works w/o having to unscrew it above the mechanical limit, you're fine. I don't know how much being 6.8 would make a difference when zeroing. If you can't zero the irons I'd say you have a real problem.

As for using a A1 post, it doesn't make that much difference. How much we're you going to use the irons vs a optic?

BSW

 

[Ehtereon11B]

If I remember correctly, front sight posts on ARs are right hand threaded. Which means you turn the post counter-clockwise to move the post up and clockwise to go down. I never saw the point of using a front post adjustment tool. Just use a round, dummy or snap cap preferred as they are not "live." If you do use a live round don't use the green tipped M855, unless you want some green flecks in your sight post.

 

[NeuseRvrRat]

Also, it has a 5 prong adjustment on the front post, and my AR front sight tool does not fit....... do I have an A1 sight?

yes. the A1 has a round post and 5 notches. the A2 front sight post is square with 4 notches.

Why would they put a non F marked FSB with an A1 post on a new mfg rifle?

maybe that height works better with 6.8 ballistics. i have no experience with that cartridge, but that's the only thing i can think of.

 

[Quentin]

Olympic, DPMS, ArmaLite, Bushmaster and others use the old non-F Front Sight Base instead of the milspec F-marked FSB on their flat top uppers. The F stands for flat top of course and the non-F FSB was used with upper receivers with integrated carry handles.

Why they do it? Who knows, but it can cause problems zeroing. Fortunately Bushmaster sells a 0.04" taller front sight post that corrects the problem and it's less than $10. It also is an A2 four sided post and should screw in your Oly FSB. I got one for my ArmaLite and it solved my zeroing problem.

 

[Infidel4life11]

Olympic, DPMS, ArmaLite, Bushmaster and others use the old non-F Front Sight Base instead of the milspec F-marked FSB on their flat top uppers. The F stands for flat top of course and the non-F FSB was used with upper receivers with integrated carry handles.

Why they do it? Who knows, but it can cause problems zeroing. Fortunately Bushmaster sells a 0.04" taller front sight post that corrects the problem and it's less than $10. It also is an A2 four sided post and should screw in your Oly FSB. I got one for my ArmaLite and it solved my zeroing problem.

On your "hobby" ARs they don't use a F marked front sight to cut cost. The OP will more than likely have a ton of windage to the left or right to get it zero'd. In the future never buy a flat top AR without an F marked FSB. Will it work? Yes. Is there better quality out there? Yes. You can also use a nail to turn the front sight up or down.

 

[Welding Rod]

My "non-hobby" BCM 20s have F marked bases and I am not crazy about them. In order to get a zero without screwing the front sight post far out I use commercial height carry handles rather than the milspec height handles I bought from BCM (which evidently are sized for the sight radius of a M4 carbine).

I ended up going to RRA carry handles. They are .040" shorter and they work well on my 20s with their F marked front sight bases. They let me screw the front sight post down so it isn't as wobbly and sticking up above the sight ears.

 

[mtrmn]

I know cost is probably the reason they use the wrong FSB, but I just can't figure out how in the world one fixed FSB could be so much higher in price than the other FSB that it would be worth it. Unless of course the cheap ones come from China...

 

[Quentin]

Olympic, DPMS, ArmaLite, Bushmaster and others use the old non-F Front Sight Base instead of the milspec F-marked FSB on their flat top uppers. The F stands for flat top of course and the non-F FSB was used with upper receivers with integrated carry handles.

Why they do it? Who knows, but it can cause problems zeroing. Fortunately Bushmaster sells a 0.04" taller front sight post that corrects the problem and it's less than $10. It also is an A2 four sided post and should screw in your Oly FSB. I got one for my ArmaLite and it solved my zeroing problem.

On your "hobby" ARs they don't use a F marked front sight to cut cost. The OP will more than likely have a ton of windage to the left or right to get it zero'd. In the future never buy a flat top AR without an F marked FSB. Will it work? Yes. Is there better quality out there? Yes. You can also use a nail to turn the front sight up or down.

Hey! My ARs aren't hobby versions! I've got BCM, Daniel Defense and PSA - all with F-marked FSBs. The ArmaLite that I corrected as described above is long gone. (J/K, I think you're talking in general...)

Windage isn't the problem when mix'n'matching the A2 height front sight and 0.04" taller rear sight on a flat top receiver - it's elevation.

 

[Quentin]

I know cost is probably the reason they use the wrong FSB, but I just can't figure out how in the world one fixed FSB could be so much higher in price than the other FSB that it would be worth it. Unless of course the cheap ones come from China...

I think the commercial makers still sell a lot of A1/A2 style uppers and rifles with integrated carry handles along with flat tops (A3/A4). They probably buy barrels with pre-installed A2 FSBes then to cut cost use the same barrels in A2 or A4 upper receivers. They know most people will never figure out there can be a problem.

If they had both kinds of FSBes on barrels, no doubt assemblers would get confused. At least the way they do it now they are consistent. And to Bushmaster's credit, they do offer the taller post to correct the problem.

Also, as Welding Rod said above RRA, DPMS, Bushmaster, Oly, ArmaLite and others sell 0.04" shorter carry handles and rear sights and no doubt recommend that you buy their rear sight, not Magpul and other milspec height rear sights.

 

[Quentin]

My "non-hobby" BCM 20s have F marked bases and I am not crazy about them. In order to get a zero without screwing the front sight post far out I use commercial height carry handles rather than the milspec height handles I bought from BCM (which evidently are sized for the sight radius of a M4 carbine).

I ended up going to RRA carry handles. They are .040" shorter and they work well on my 20s with their F marked front sight bases. They let me screw the front sight post down so it isn't as wobbly and sticking up above the sight ears.

Smart move! Also, the $10 Bushmaster taller sight post would allow you to use milspec height rear sights.

 

[Infidel4life11]

Quentin, I was talking in general about the bushy's, dpms, oly's and armalites my friend. I've owned it all it seems. I found there is nothing wrong with the "hobby's" if we're using them for their intended purposes. Just got a PSA the other day pretty excited about it.

 

[Quentin]

I think you'll really like the PSA, Infidel. They do everything right yet hold their price to the level of the hobby ARs. So there's no reason to buy the hobby gun when you can have milspec for the same money. My PSA compares well to my DD and BCM.