20” rifle upper on M4 lower?

[Galbraith]

I’ve been wanting to set up a full length govt profile 20” upper receiver group, but I’m not a fan of a fix stock. I already have a couple of M4 lower receiver groups set up with carbine buffer tubes that I would like to mate the upper to. Are there any mechanical/reliability concerns with combining these two? Thanks.

[ssb]

It may be a safe bet to install a VLTOR A5 receiver extension on your chosen lower and go with that buffer setup.

[littlejerry]

Have used both CAR buffers and A5 setups with my 20" Colt. Never had function issues either way.

[Cory]

It's completely doable. In fact, it's been done with USGI rifles. I think someone said to run H6 or H7 buffer.

A clone group I follow had this posted earlier this month. Apparently a Corpsman with 1st tanks.

43078

-Cory

[Bigghoss]

There's currently an active thread on this.

https://pistol-forum.com/showthread.php?38744-Carbine-Buffer-and-Rifle-Gas-System

[SecondsCount]

Years ago I ran a carbine buffer with a 20" Bushmaster upper without any issues.

Not the same, but I run a carbine lower with a standard buffer behind an 18" Faxon barrel using a rifle length gas system. Never had an issue.

[John Hearne]

This is an application tailor made for the VLTOR A5.

[Xrslug]

Canada ran this set up — C7A2 I’m pretty sure it was

[MistWolf]

...Yes, you can use a rifle upper with a carbine lower...Lowers with H, H2, A5H2 or rifle buffers (used in the correct RE with the right spring) will work with any properly gassed upper.

[HeavyDuty]

This is an application tailor made for the VLTOR A5.

I loves mine.

[MistWolf]

20" Upper + A5H2 + Battlecomp = Soft & Flat Recoil

[DocGKR]

One of my favorite AR15 configurations!

[JRB]

Saw a pair of interesting ones yesterday - two M16A2's carried by E4's from an HHC element, both with the M4 buttstock conversion and the KAC rail system. One had an M68 CCO on a carry handle gooseneck, the other was on the A2 irons. No PEQ's or Surefires or anything on the rails, just added weight.

The most fasicinating part was the M68 CCO equipped example was a GM Hydramatic M16A1 receiver that had been rebuilt into an A2 at ANAD in 94 according to the mag well stamps. The gun was a total mutt - an Emco upper with an FNH barrel, too.
I was tempted to ask the SPC to look at the BCG just to see if it was a mutt too, like the other GM Hydramatic A2 rebuild I encountered some 8-ish months ago doing an arms room inventory.

Wish I'd had a chance to get a picture. Weirdest rifle I've ever seen in active service.

[revchuck38]

<thread drift>

Way back in '88 I was the CO of an HHC. We had M16A1s that were apparently rebuilds; IIRC they were stamped XM15E1. We also had three M3 grease guns for the maintenance section's M578. I could never get ammo for them for qualification. :(

</thread drift>

[JRB]

<thread drift>

Way back in '88 I was the CO of an HHC. We had M16A1s that were apparently rebuilds; IIRC they were stamped XM15E1. We also had three M3 grease guns for the maintenance section's M578. I could never get ammo for them for qualification. :(

</thread drift>

Such a rifle was most likely marked XM16E1, not XM15. Damn shame you couldn't get ammo for the M3! I've read that M3 grease guns held on in little nooks and crannies of the National Guard through the mid 90's.

Years ago as an E4, I found 5 grease gun magazines and an M14 magazine in an ancient box of mixed BII while doing a wall-to-wall inventory of some ancient conexes. I asked my SSG if I could keep even just one, sadly no - all had to go to DRMO.

[revchuck38]

JRB - I googled "XM15E1" and came up with numerous hits, also XM16E1 came up often. Looks like they were both early issue versions of the M16 series.

[Suvorov]

Such a rifle was most likely marked XM16E1, not XM15. Damn shame you couldn't get ammo for the M3! I've read that M3 grease guns held on in little nooks and crannies of the National Guard through the mid 90's.

Years ago as an E4, I found 5 grease gun magazines and an M14 magazine in an ancient box of mixed BII while doing a wall-to-wall inventory of some ancient conexes. I asked my SSG if I could keep even just one, sadly no - all had to go to DRMO.

We had them in a locker in my Company until 2003. The weren’t on our books at the CO but my readiness nco assured me they were accounted for. I was more than willing to buy the 45 ammo for them but alas- there were no magazines. I left the company to staff. When I returned to take command the M3s were gone. Apparently to the depot but I can’t help but secretly hope one of my gun loving senior ncos liberated them.