10.5" MRP Components Questions

AR/M4 AR Technical Discussion
1

Ok guys,

I’m building my first SBR AR-15 based around a MRP 10.5" upper and want to make sure I’m setting it up with parts that will allow it to perform at peak potential.

The first thing I got was a Young Manf. Chrome M16 profile bolt carrier…I just liked the pretty color. Does anyone see any problem with this carrier? It seemed to fit really tight in the upper at first, but after I cycled the action 5-10 times it seemed to move fairly normal in the receiver.

Secondly, I had a Enhanced LMT Bolt that I’m going to use. This also seemed to fit a bit more tight than normal within the bolt carrier. It looks cool, but I want function more than anything…are there any known issues with this bolt in a SBR? I kinda wish I just stuck to the standard bolt but it’s too late now.

Third, I’m not sure what weight buffer to use. I originally planned on an H2, but have read a few posts about the LMT 10.5" guns and how LMT recommends an H buffer…but I may be wrong. What do you all think?

Thats about all I’m concerned about. Aside from that, the upper is just waiting for a nice Magpul lower to sit on…Can’t Wait for that!

Thanks for any input!

-Mike

2

In my 10.5" MRP I use a standard LMT M16 BCG, LMT H buffer and regular carbine buffer spring on the advice of WES at MSTN.
This is on a SBR Bushmaster semi lower with a LMT 2-stage trigger.

I have had ZERO failures to feed, fire, or extract with many rounds of M855 (LC & Winchester), MK262, BHBB 75gr, Hornady 75gr (both .223 & .556 loads), Win STHP 55gr both with and without the SpecWar2 suppressor.
I have a enhanced LMT bolt/regular M16 carrier in my 14.5" which shoots M855 almost exclusively, but I’ve never run one in a 10.5" and my understanding was that the enhanced bolt was actually ok in the 14.5" although I’ve heard it wasn’t, but that the enhanced carrier is for 14.5" only.