Rebuilding a BCM Carbine Upper

AR/M4 AR General Discussion
1

I was wondering what the viability of rebuilding a carbine length BCM upper with a 14.5 in barrel and the A2X hider with a longer rail and low profile gas block would be.

There’s a new build in the background that will start out as a mid length plus a 14.5 in barrel with a battle comp.
However, I’d like to be able to get the same length grip
on the BCM upper without buying a completely new upper if possible.

Not exactly sure where they start the measurement on the rail length but it looks like a 12 inch rail will fit and give me
the grip length I’m searching for. Just wondering if anyone would have some recommendations of rails and gas blocks that would work together to pull this off.

The BCM currently has an MI two piece rail installed and measures 6 1/8" from rail to rail or 7" if measured from where it goes
into the Delta ring assembly to the hand guard cap. Either way it looks like a 12 inch rail will give the reach I’m trying to get an not go past the end of the barrel.

I’ll keep digging on my own and try to find some that are compatible but was hoping a few here might already have some answers.

2

Here’s a 14.5 with 12.0 lite rail for reference.

You’ll need to remove the permed FH to replace the barrel nut for all the rails I can think of.

3

The new centurion c4 rail clamps to a standard barrel nut and is available in 12". There may be others but the centurion advertises ability to install without removing fsp or perm attached muzzle devices.

You would have to shave your current fsp, and cut off the delta ring and handguard cap, these can all be done without removing them or your muzzle device from the barrel.

4

That’s the way to go.

5

I agree. I think that the Centurion rail is definitely the option for those that have some permed stuff going on or can’t remove their FSB. I have been tinkering with the 10" one that I got and I have to say it is a nice piece of kit.

6

Thank you everyone, those are some good ideas and parts to check out.

I kind of like the idea of just shaving the FSB instead of removing it and replacing it with something that would end up being the same size anyway and possibly not line up 100% with the pin holes.

I would like to replace the A2X with a battle comp but keeping this rebuild as simple as possible will allow the next build to have more of a budget while still achieving some important goals on the rebuild.

Thank you again.

7

I would take a serious look at the DD omega X. The std barrel nut and delta ring assy leave alot to be desired. And after seeing how the omega x fared in the DD torture test I would say its good to go.

8

You still need to remove the FSB to get the handguard cap off.

9

Not if you cut off the hand guard cap.

10

Hmm… although I have cut the delta ring my self and found it to be a relatively easy task, I cant seem to convince my self to do the same with the cap. It seems like theres just no way of being able to do it without either scratching the barrel or FSB.

If you have a link to some one doing this please post, I am interested!, sorry for slight hijack.

11

It can be done with patience. I have cut a few caps off. I also won’t get bent about a little scratch unless it belongs to someone else.