Rifle upper on carbine lenght lower?

[cd228]

IIRC the Canadian C7A2 rifles were 20" rifle length gas systems. Colt Canada used to offer a version with an H2 buffer in it, but I don't know the gas port size. On the US Army side, I once saw an article in PM magazine with the parts and part number to change the stock of an M16 to a collapsing model. I forget which edition. The article emphasized that the rifle would have to be returned to it's original configuration to be turned in. Shortly thereafter the Army announced that it was going to standardize onM4A1s for everyone.

[Junkie]

Recoil system is completely independant of gas system length.

True, but a rifle buffer is significantly heavier, so I suspect ideal port size is different for rifle buffer vs carbine or H buffer

[ColtSeavers]

True, but a rifle buffer is significantly heavier, so I suspect ideal port size is different for rifle buffer vs carbine or H buffer

Every recoil system has different wieght buffers, even rifle length. The point remains the same.

Regarding recoil system:
Step one: decide on desired recoil system.
Step two: fine tune recoil system.

[26 Inf]

True, but a rifle buffer is significantly heavier, so I suspect ideal port size is different for rifle buffer vs carbine or H buffer

I have built several 18 inch uppers using rifle length gas systems, they have been plug and play on the carbine receivers I've mounted them on. I pretty much use H buffers, though.

[5.56 Bonded SP]

I run a rifle upper on a carbine lower, functions flawlessly.
H buffer with 18'' barrel .0935 gas port running with no malfunctions, I plan on increasing buffer weight at some point. However, this setup I have has the least muzzle jump of any of my AR's, and right now all my AR's currently have bird cage flash hiders.

[5.56 Bonded SP]

True, but a rifle buffer is significantly heavier, so I suspect ideal port size is different for rifle buffer vs carbine or H buffer

Most rifle length uppers have roughly .0935 gas ports if I recall correctly.

[ExplorinInTheWoods]

It's good to go. I built a lower with a SSA-E and i have a Colt 24" bull barrel varmint type gun and it has a milspec trigger and it's a clover leaf gun so I decided what heck and put that upper on the lower with the SSA-E and carbine buffer tube with a spike's T2 buffer.

[Amicus]

Some years ago, for pure S&G, I replaced a rifle recoil system with a carbine system (H buffer) and gave it to a guy in a class to use. The rifle was an A2 type (probably only used for DCM/CMP) made by Colt that I had just picked up at a store, probably manufactured 1990 or 1991.

The extractor failed completely. It was very embarrassing. Lots of mortaring. But I was stupid as I had only cleaned it, changed the recoil system, and put maybe 10 rounds downrange.

I took it home, thought about it, replaced the original extractor spring (now about 20 years old) and the thing ran like a champ. Still does.

[5.56 Bonded SP]

Some years ago, for pure S&G, I replaced a rifle recoil system with a carbine system (H buffer) and gave it to a guy in a class to use. The rifle was an A2 type (probably only used for DCM/CMP) made by Colt that I had just picked up at a store, probably manufactured 1990 or 1991.

The extractor failed completely. It was very embarrassing. Lots of mortaring. But I was stupid as I had only cleaned it, changed the recoil system, and put maybe 10 rounds downrange.

I took it home, thought about it, replaced the original extractor spring (now about 20 years old) and the thing ran like a champ. Still does.

You can't use carbine buffers in rifle buffer tubes or vice versa. Rifle buffer tubes can only use rifle buffers/springs, and carbine buffers can only use carbine springs and buffers. You can mix uppers, but you can not mix rifle buffers/springs with carbine buffer tubes and vice versa.

Rifle buffers are longer than carbine buffers, and carbine buffer tubes are shorter than rifle buffer tubes, these items can not be mixed. A carbine buffer in a rifle buffer tube will travel back too far, and if you put a rifle buffer into a carbine buffer tube the BCG won't even go all the way back.

Uppers can be mixed with different buffer systems, but rifle and carbine buffers aren't interchangeable with their buffer tubes.

Hopefully that makes sense.


ETA picture reference

Rifle top, carbine bottom



Carbine top, rifle bottom

[5.56 Bonded SP]

Colt Canada uses a rifle length upper on a carbine lower for their standard issue C7A2 IIRC

Here is a pic




Rifle uppers on carbine lowers are GTG