I was wandering if the true Colt M4 handguards will fit a Bushmaster carbine?  The reason I am asking is because there are two different diameter handguard caps that are offered by Colt.  One is  HANDGUARD CAP, CARBINE (ROUND), 0.625, XM177E2 and the other is  HANDGUARD CAP, CARBINE (ROUND), 0.750, M4/M4A1.  Will I need to change to larger diameter cap to be able to use the M4 handguard on a Bushmaster?  If I need to switch caps, how do you do so?  I have a permanently installed phantom on the barrell.  Thanks for the advice.

Yes, they will work.


The handguard cap is the piece on the barrel, so that won't make a difference to you.

Why would they offer two different diameter caps?  Just seems odd to me.

I believe I just answered my own question.  The different diameter is really the diameter of the cutout for the barrell (correct).  I was thinking there was a difference in the diameter of the "securing point" on the handguard itself.  It seems too easy now that I think about it.  Thanks.

They work and fit on my Bushy just fine. And the Cav Arms handguards are the ones to get.