Need SBR build help

[Lee Indy]

My can was finally released from NFA jail. And Im ready to build my 300 upper.

Im tring to figure out barrel length.
Currently looking at an ar stoner 7.5 or a 8in ballistic advantage. Problem im facing is finding a rail that fits the 7.5 and will let the asr flash hider and the can attach without rubbing but close as possible.

I was set on the 8in BA barrel and the 7in KMR then found the ar stoner barrel for 69 bucks vs the 155 for the BA barrel.

[IraqVet1982]

I don't think you'll notice a difference...

http://www.ballisticsbytheinch.com/223rifle.html

[Lee Indy]

Question is what rail for the 7.5 barrel. The kmr appears to be too long to allow the asr flash hider to engage.

[themonk]

FYI most rails are longer than advertised. SLR is your best bet as they make a rail for every barrel length.

[Lee Indy]

Thats what Im looking at. If my measurements are correct I have 7.18 inches of room for a rail

[triggerguard]

Thats what Im looking at. If my measurements are correct I have 7.18 inches of room for a rail

Maybe you'd already put it all together but I can 2nd the recommendation for SLR Rifleworks. They have 6.7" and 7" rails. I've used their rails in two other builds and they've both been solid, but a little underused. One is a 14.5" barrel and 13.7" hand guard. The other is a 9mm AR with a 5" barrel and 5.5" rail.

The general rule I follow is that the barrel length should be 0.625" longer than the hand guard. But...

If you're using an ASR flash hider with the wrench flats in the rear (towards the chamber) it gives you about 1/8th of an inch standoff from the shoulder so you only need a 0.5" difference between rail and barrel lengths but you may need to remove the rail to change the muzzle device. An example is a build I did with a Centurion Arms CMR 11" rail (10.994 inches long) on a 11.5" barrel capped with an ASR flash hider and a Saker K556. The silencer locks up with the slightest clearance.
Beware that the ASR brake doesn't have the wrench flats in the back though so you'll be stuck using the flash hider. Also, if you want to go to a different brand there's less flexibility if you go with this minimal clearance.

[HMM]

Little bit of a:
https://upload.wikimedia.org/wikiped..._Bump_Sign.JPG

But I will second SLR Rails, I have them on all my rifles. They are great!