BCM 11.5" KMR SBR upper question

[themonk]

I have been perplexed lately and maybe you guys can help me out.

I was thinking of building a new 10.3 upper on a BCM receiver, 9"KMR or 9.5 geissele rail and a 10.3�� Daniel Defense barrel. At the same time I keep looking at the BCM 11.5" KMR upper and my only issue really is its a longer barrel. This upper will run suppressed 99% of the time. It will get mated to a lower waiting on paperwork and would be my go to rifle for 556.

Any thoughts either way 10.3 vs 11.5 suppressed?

[TehLlama]

1" or barrel length isn't going to change a ton as far as feel and balance, and the 11.5" BCM will probably be smoother than the 10.3" across every sample (read up on the gas post sizing for the Mk18 length DD barrels). You'll save some cash sticking with an all BCM upper, they're measurably nicer to the can that will live on that upper, and it's still a bit more MV. Coming from somebody who owns a 10.3" dedicated suppressed SBR: get the 11.5" if you can, you'll like it better.

[VIP3R 237]

TehLlama summed it up almost perfectly. Go with the 11.5, it's the better option overall.

[GeorgeB]

Have you read BCM's reasons for advising 11.5"?

If not, here it is.

http://www.ar15.com/forums/t_2_138/1...the_10_5_.html

[themonk]

1" or barrel length isn't going to change a ton as far as feel and balance, and the 11.5" BCM will probably be smoother than the 10.3" across every sample (read up on the gas post sizing for the Mk18 length DD barrels). You'll save some cash sticking with an all BCM upper, they're measurably nicer to the can that will live on that upper, and it's still a bit more MV. Coming from somebody who owns a 10.3" dedicated suppressed SBR: get the 11.5" if you can, you'll like it better.

Super helpful - Thanks!

[hf0311]

I've been using an 11.5 with a 9.5 Geissele rail for over a year, its an awesome setup and I love it, but I would rather have the BCM KMR on it. Especially running it with a can, that tiny wait savings that the KMR offers over the Geissele ends up making a fair enough difference. Its not enough to make me sell my upper and get the BCM or anything but its enough to make me recommend the BCM over my setup.... For me, looking at I objectively 11.5 seemed the best way to go for my SBR needs..

[JG007]

how much is a light weight rail (or LW barrel) really going to matter on a short barrel, and is it worth the trade off?

[jstalford]

Buddy of mine has a Noveske 10.5 and a BCM 11.5 and same as everyone else, prefers the 11.5.

[Tigereye]

Based on Tehllama's and other's recommendations, I went with the 11.5 w/ KMR and couldn't be happier. I shoot it suppressed a little more than half the time.

[domestique]

IIRC, I believe Crane initially went with the 10.3" is because that's where the barrel profile changes in relation to the grenade launcher. They were also more size oriented as SOCOM needed the rifle to be able to go through bulk heads sideways.

I have a 11.5" BCM KMR and it has run like a top with an H2 buffer both suppressed and unsuppressed.