BUIS Problem (RRA Barrel) > Optics, Mounts, and Sights

Posted: 2/20/2006 3:41:03 PM EDT

I recently found out RRA does not make a "F" fsb. Too late eh? Well, I also read there are TWO heights of sights, commercial and military.

Is this the same for BUIS? Which are commercial or mil? Or all of them military? This in a real pain in the ass.

Help a newb out. I searched for "FSB" and read what came up but most of the threads just dead-ended with no final answer.

Posted: 2/20/2006 3:58:07 PM EDT

[#1]

www.del-ton.com/detail.aspx?ID=1162

Whoa! I may be kinda in the dark. But I am betting this will fix it.... being its .030 taller which is the difference between the two.

EDIT: This still bears the question, are there two heights of flip BUIS?

Posted: 2/20/2006 4:10:01 PM EDT

[#2]

I would think not?

Posted: 2/20/2006 4:44:47 PM EDT

[#3]

Well I sure hope I find out before I plop down $80 for one.

But I bet most of the manufactures are mil because that is who they designed their stuff for.

Posted: 2/22/2006 2:45:50 PM EDT

[#4]

Just one height for most BUIS.

Posted: 2/22/2006 3:25:58 PM EDT

[#5]

I have a RRA midlength with an ARMS BUIS and I had to turn my front sight down so many clicks I forgot. It's definitely not sticking out too far...

Posted: 2/23/2006 3:27:06 PM EDT

[#6]

I talked to someone at RRA and they claimed to have switches to the flat-top height FSB 2 years ago on their built rifles. He also said ADCO would probably be shipping those barrels too.

So I lucked out I think. Teach me to double-check next time.

Posted: 2/24/2006 2:03:37 PM EDT

[#7]

RRA is using "F" FSBs now? That's news to me. I got an upper from them about 2 years ago and it's not marked "F" and it works with a BM carry handle so as far as I know it's not "F" height.

The two heights are only .040" different and not everybody has a problem if they're mixed. But some do. If you do end up with a "mil" rear BUIS and have trouble you can get a taller front sight post to make up the difference. It puts the top of the front sight the same as if you had the regular one on an "F" base.

As a general rule the "mil" rear sights are ARMS, Troy, LMT, LaRue and the "commerical" are BM, DPMS, YHM?, etc.

Posted: 2/24/2006 4:30:38 PM EDT

[#8]

I've got a RRA mid-length barrel that I've had for at least 3 years, and it has the F front sight base.

In fact, I've had two from RRA, purchased about 2 months apart. The first one had the F base, a second one did not. Both of them worked with the ARMS #40 without any issues at all, although I do remember the "non-F" having to be adjusted pretty far out.

As you can see, I still have the one with, but I can't prove it's a RRA any more, as it's been profiled and fluted. Before that, the 1" thick under the handguards is unmistakeable.

Posted: 2/24/2006 6:14:04 PM EDT

[#9]

Quoted:
As a general rule the "mil" rear sights are ARMS, Troy, LMT, LaRue and the "commerical" are BM, DPMS, YHM?, etc.

Hopefully the YHM I ordered is correct then.

Posted: 2/27/2006 7:03:49 AM EDT

[#10]

Quoted:
i48.photobucket.com/albums/f240/slaughterhouse1/Rock%20River%20Barrel/th_44613dce.jpg i48.photobucket.com/albums/f240/slaughterhouse1/Rock%20River%20Barrel/th_da34b897.jpg
As you can see, I still have the one with,

I think mine is marked like that, but I don't think that's the "F" they're talking about, just a forge code. IIRC the "F" is on the other side (left side) and stamped in by itself, not raised.

Posted: 2/27/2006 7:08:57 AM EDT

[#11]

Quoted:
Quoted:
As a general rule the "mil" rear sights are ARMS, Troy, LMT, LaRue and the "commerical" are BM, DPMS, YHM?, etc.

Hopefully the YHM I ordered is correct then.

I put a BM handle (from the EE here, claimed to be BM, and the windage knob is purple so it must be

) on my RRA upper from 2 years ago and it worked fine. A lot of YHM stuff is sold through BM, which uses the "commerical" height, so I'm assuming all of theirs is that height. Following that logic, with the assumptions, then the YHM should work on your RRA. If it doesn't, they make taller front sight posts.

Posted: 3/11/2006 3:10:10 PM EDT

[#12]

Quoted:
RRA is using "F" FSBs now? That's news to me. I got an upper from them about 2 years ago and it's not marked "F" and it works with a BM carry handle so as far as I know it's not "F" height.

The two heights are only .040" different and not everybody has a problem if they're mixed. But some do. If you do end up with a "mil" rear BUIS and have trouble you can get a taller front sight post to make up the difference. It puts the top of the front sight the same as if you had the regular one on an "F" base.

As a general rule the "mil" rear sights are ARMS, Troy, LMT, LaRue and the "commerical" are BM, DPMS, YHM?, etc.

I found the email...

Hi,

If you ordered a 16” rifle, you DO have a taller front sight housing, so no problems should be incurred finding a rear sight to work with it. We switched to a carbine height FSH almost two years ago.

Thanks.

Steve/RRA

Sorry for the necro-post, but I figured it would be best to not leave it hanging.

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[ARCHIVED THREAD] - BUIS Problem (RRA Barrel)

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