New BCM rail

[scooter22]

There's a very good article in the new issue of Combat Arms on the new KMR uppers. It included a picture of the stripped ELW barrels as well. It stated a 0.625 oz. weight savings on a 14.5 barrel. An interesting note, it also discussed the Mod1 comp and described it as having an expansion chamber that improved reliability of the 14.5 midlength barrel. I had not heard that before. Overall, it's a good article. The issue had some of the best written articles I've seen in a print magazine in a long time.

What does that even mean?

[mtdawg169]

What does that even mean?

The article indicated that the Mod1 comp had a small chamber in the rear of the device, whose purpose was to increase reliability by affecting how gasses escape from the barrel. It essentially said that the small expansion chamber increased the dwell time of the barrel.

[ESK]

You are correct. Any enclosed chamber is in some respects an expansion chamber. Some comps and/or flashhiders are better then others. The Mod1 has a very small chamber, but it still tricks the weapon into thinking it has an inch longer barrel (after the gas port) than it does... Any increased dwell time is a benefit, especially for a 14.5" middy.

It essentially said that the small expansion chamber increased the dwell time of the barrel.

[mtdawg169]

You are correct. Any enclosed chamber is in some respects an expansion chamber. Some comps and/or flashhiders are better then others. The Mod1 has a very small chamber, but it still tricks the weapon into thinking it has an inch longer barrel (after the gas port) than it does... Any increased dwell time is a benefit, especially for a 14.5" middy.

Thanks ESK. Is that feature found on both comps or just the Mod1?

[markm]

Interesting. I did about 10 rounds with the A5 H4 buffer on the 14.5 middy I'm running an to my surprise, it cycled just fine.

[mtdawg169]

Interesting. I did about 10 rounds with the A5 H4 buffer on the 14.5 middy I'm running an to my surprise, it cycled just fine.

I'm running the A5H2, Springco Green and LMT enhanced carrier. The he only issue I've had was with a few rounds of Tula, which was to be expected and is an ammo issue. The only failure was a failure to lock on empty. Same results with a standard BCM carrier. I'm undecided about the E carrier in the 14.5 midlength.

[ESK]

Just the Mod1 and the 762 Comp.

Thanks ESK. Is that feature found on both comps or just the Mod1?

[markm]

Thanks ESK. Is that feature found on both comps or just the Mod1?

Looks like just the Mod1. I'm going to add one of these to my other 14.5 middy at some point.

[jcalvert86]

Interesting. I did about 10 rounds with the A5 H4 buffer on the 14.5 middy I'm running an to my surprise, it cycled just fine.

A5H4 in my BCM 14.5" middy w/ Sprinco green.. zero issues.

All I ever shoot is bulk xm193 though.

[markm]

A5H4 in my BCM 14.5" middy w/ Sprinco green.. zero issues.

I'd love to pop the H4 back in and run the ELW on a full auto lower.