Converting an M4 Carbine

[dsteed08]

Hey everyone! I have a bushmaster M4 carbine and was wondering what I need to change in order to make it to shoot 300 blk ammo (both sub/regular. Not sure this makes a difference) I've heard it's easy but wanted to make sure I didn't do anything stupid before hand. Or should I just "bite the bullet" so to speak and buy a 300 blk rifle? I've heard anything from just the barrel to switching out most of the gun parts. I'm looking to do a permanent conversion. Thanks a million!!

[Koshinn]

Hey everyone! I have a bushmaster M4 carbine and was wondering what I need to change in order to make it to shoot 300 blk ammo (both sub/regular. Not sure this makes a difference) I've heard it's easy but wanted to make sure I didn't do anything stupid before hand. Or should I just "bite the bullet" so to speak and buy a 300 blk rifle? I've heard anything from just the barrel to switching out most of the gun parts. I'm looking to do a permanent conversion. Thanks a million!!

Barrel. Also a gas tube and gas block if you're not going to re-use the ones you already have, plus a rail/handguard as I'm assuming you have a front sight block currently installed.

But strictly speaking, the only absolutely necessary thing to change is the barrel.

Do you have a big-ass vice or access to one? Do you have a barrel block or upper receiver block or "reaction rod" type of thing to hold your upper in place? Do you have a barrel nut wrench and a torque wrench? Do you have moly grease on hand? You'll need these things to replace a barrel, and the cost is enough that if you never plan on re-barreling ever again, you're better off paying a gunsmith to do it all for you.

[SteveL]

If you want to be able to switch back and forth between .300 blk and 5.56 then just buy a .300 blk upper and drop it on your lower. If you want to switch to .300 blk exclusively then you can rebarrel your existing upper.

[Junkie]

I agree that it's worth spending a little extra to get a complete upper. I'd rather not share a BCG between two uppers but it's pretty easy to do if you want to swap back and forth but don't want to spend much. If you want to swap back and forth, I'd recommend against changing out the barrel itself with any frequency... I'm not sure how long the threads would last doing that, plus you'd have to re-zero after each time you swap barrels.

[26 Inf]

Just for fun:

16' Barrel - 167.95 http://www.gmriflebarrel.com/gm-m27-16-300-blackout/

BCM Upper Receiver - 119.95 (didn't see any blems)

PSA Upper Receiver - 99.95

PSA Charging Handle - 22.95

Barrel Nut (won't need with ALG Rail)

BCM Bolt Carrier - 169.00

PSA Bolt Carrier - 99.99

ALG 13" Ergonomic Modular Rail - V2 Black 155.00

Geissele Super Gas Block 39.00

Gas Tube (carbine length) - 14.99

You assemble - 599.99 (PSA upper receiver and BCG) 689.75 (BCM upper receiver and BCG)

You buy upper - Bushmaster 16" 739.99 (Midway) CMMG 16" 689.99 (Midway)

Complete Rifle -

Bushmaster - 1471.00
Noveske 18" Rogue Hunter - 1895.00
Noveske Recce Basic - 1730.00

I'd build an upper, but that's me. Hey, I'm on vacation.