What's up with the price of Colt LE6921CR upper halves

[Stickman]

Out of curiosity, does the KAC ambi mag release dig into the lower?

Yes, it certainly does. Its not digging in the way some junky optic mounts do, but it does rub lightly against the surface.

[Bret]

I put a LE6921CR upper half on my Colt M16 lower and ran 100rds of Fiocchi 223Rem 55gr FMJ through it. As you'd expect, it was 100% reliable. The cyclic rate seemed perfect.

[maca1]

What’s the recommended spring/buffer combo for these?

I run Blue/H2 in mid-lengths. Is the recommended carbine set up the same? Thx

[markm]

For Carbine, the Colt carbine spring and H2 buffer. Any rifle or A5 buffer systems is great too. Mine is running smooth with the Vltro A5 standard system.

[Bret]

I'm running the carbine spring and an H1 buffer. The full auto cyclic rate seems perfect and the ejection is about six feet. There are no smears on the case heads or dings on the case walls.

[markm]

I'm running the carbine spring and an H1 buffer. The full auto cyclic rate seems perfect and the ejection is about six feet. There are no smears on the case heads or dings on the case walls.

H1 will work, but I bet you'd like the H2 better. Were you here when RSilvers posted that analysis of the Carbine buffer weights? The bottom line is the H2 most closely resembles the Rifle buffer.

[Bret]

I'll try it. My bet is that it will work just fine.

[markm]

I'd love to hear if you can tell a difference between the two.