Bolt Carrier Group weirdness...

[halfmoonclip]

Not long after the Clinton ban sunsetted, built a replica of the M16A1 that the gummint was kind enough to loan me in 1970. Upper, BCG, and furniture was all NOS Colt; NoDakSpud period correct lower; ran great, shot really straight.
I'd seen the early AR 16" carbine uppers at Brownells, and scored one reasonably at a gun show; no BCG, but I used the Colt one, and it ran fine.
Like the setup; full sight radius in a carbine, for using irons, but it is a rifle gas system...lack of dwell time was reputed to cause trouble. Reputedly, the Brownells replicas use a bigger gas port to compensate.
Popped another random BCG in, rather than swapping back and forth...and it ran sporadically.
Scored another Colt BCG at a show; this, a half circle carrier, likely from an SP1.
This one runs just fine.
So, no big deal, but what would make a difference? Same 55 gr milspec ammo in both cases?
Thots?
Moon

 

[someguy2800]

Leaky gas key? Leaky firing pin hole? Different weight?

 

[halfmoonclip]

Getting the lighter, half circle, carrier was a motive in buying it.
Some years back, when I was active on Arfcom, the full circle carriers were much preferred to older, SP1 ones; Colt made them that way so they wouldn't work with an autosear.
The rifle length systems in a 16" carbine was reputed to be an issue.
Moon

 

[12Bravo20]

The rifle length systems in a 16" carbine was reputed to be an issue.

And they are still a problem. That is why most of the Dissipator models you see will actually use a carbine gas system hidden under the handguards.

 

[CarJunkieLS1]

Why anyone would think a rifle gas system on a 16" barrel is a good idea is beyond me.

For a reliable shooting and a little softer shooting the mid length gas system is a far better option.

 

[mjsdwash]

didnt colt Rockset their key? Thats the only gas difference i know of.