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1/25/2018 7:38:29 AM
Posted: 12/21/2005 3:02:23 PM EST
SEARCH didn't hit it.

Does it exist?

Link Posted: 12/21/2005 4:08:36 PM EST
Ask Tweak, he might have a link.
Link Posted: 12/21/2005 4:29:06 PM EST
There should be some info on FSB height with flat top receivers. I had posted some questions on it around six months ago, and got some pretty good responses. I had an issue with a Bushmaster barrel, RRA flat top, and ARMS 40 BUIS. Found out you have to use an extended front sight post in order to zero, or get a barrel that has a properly set FSB height. One brand was mentioned with the proper FSB height (shhh, its Colt), but the important thing to check for is a "F" stamped FSB. Apparently such a "F" marked FSB is the proper height for a flat top reciever.
Link Posted: 12/21/2005 4:59:54 PM EST
A F stamped FSB is necessary for any short (shorter than 20") sight radius application, A1, A2, carry handle, BUIS or flat top. You can get around this by buying a .040" taller front sight pin from brownells. If you have a F post or a long pin on a long barrel, you just screw it in a few more clicks. If you have a short post/pin on a short barrel, your pin is going to be sticking up above the flat of the post, being all wiggly and stuff.
Link Posted: 12/21/2005 5:07:20 PM EST
Link Posted: 12/21/2005 5:37:00 PM EST
Many thanks. Bear with me here please ...

So when starting from scratch (RRA upper) and building a flat top with a 16" bbl ... I need to order the taller front post from Brownells when using ANY FSB I purchase or ... any FSB other than an F marked Colt ... is that correct?

AND ... will the taller post stick up over the protective ears in most correctly assembled builds?

Please forgive my ignorance.
Link Posted: 12/21/2005 5:57:43 PM EST
Link Posted: 12/21/2005 5:59:31 PM EST
Roger that.

Thanks man.

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