12.5" upper question

AR/M4 AR General Discussion
1

I’m helping someone plan a 12.5" pistol build and we have a question. He’s 100% sure he wants a quad rail and a fixed front sight. He’s debating between a 12.5" BCM carbine and a 12.5" BCM Kino.

Would it be ill advised to run a 12" Centurion Arms C4 FSP with a 12.5" carbine upper? The thing we’d be worried about would be the muzzle blast being only about a half inch from the end of the rail. Is that something to be concerned about, or would it be okay? I’m not sure if it matters, but the gun would have an A2 flash hider, and perhaps a 3-prong down the line (in other words, no crazy muzzle brake or comp).

Here’s the rail: https://www.centurionarms.com/product-p/06012-p.htm

The 12" cutout rail only works for a carbine length FSB, so if it’s a bad idea then a Kino with a 9" or 10" cutout rail is the preferred choice.

2

I used to have one of those, the end being that close is not a problem.

3

It will only be a problem if it goes under the rail. If you want some shining examples of this type in “muzzle brake under rail” into the google machine.

4

My SBR is a 12.5 Kino and it previously had a slick Noveske that length. Either will work fine. I usually prefer the slick rail without a FSB but in the case of the Kino with an T-1 it just seems right, handles and shoots great. I’ve still got a C-4 rail on it and I actually like the balance point and weight on the set up.

5

If you’re feeling adventurous I’ve seen some pictures of guys cutting down MI rails to use a rail with a FSB.

A Samson evolution rail set up for piston conversions may work without cutting, would have to check the measurements of the kino.

6

He went with a kino and a 10” Centurion C4.

Stick, got any photos of that setup?