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10/17/2015 1:00:01 AM EDT
So I'm obviously new to ARs. Trying to figure out what I want to do with a couple rifles I sort of built. I say sort of because all I did was assemble the lowers, I bought the uppers complete.

So I bought a one of PSAs CHF 16" mid length barreled uppers, came with an end cap that looks like a triangle. I took it down to a local FFL and bought a Troy rail to put on it. Ok great. But I just recently bought a very cool Colt upper and barrel that has a round shaped end cap. So now I'm confused. Are there rails and/or handguards I can't use with this type? I realize free float won't work without removing the end cap etc. any help is appreciated
10/17/2015 3:44:03 PM EDT
[#1]
All normal m4/m16 type(non-freefloat) handguards should work with either the round or triangle cap.

 
10/17/2015 5:09:11 PM EDT
[#2]
Ok thanks. So most drop in quad rails should work just fine?
10/17/2015 5:24:58 PM EDT
[#3]
Rifle gas system, triangle

Midlength gas system, triangle*

Carbine gas system, round

There is no standard for midlength gas systems, but the triangle cap is the most prevalent

Things like the magpul sl handguards only work with round handguard caps, but most drop in rails and handgaurds use both
10/17/2015 8:14:01 PM EDT
[#4]
Perfect. Thanks for clearing that up for me
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