05-25-2011, 12:27 AM
Gents,
That 10.25" barrel CQBR upper is a SOCOM project that is meant to reduce the M4 profile for Close Quarter Battle, especially when used with a suppressor. If you look at the shoulder patch of the dude in the picture carrying the CQBR upper-equipped M4, it says it all.
That gas system and barrel length are more problematic with the AR15, even with a gas port diameter of .093". I have a friend who's waiting on a broken shell extractor right now for his. The Army learned this back in the 1960's with the 10" barreled XM177E1, before increasing the barrel length to 11.5" on the XM177E2, as well as using the moderator with baffles to increase back pressure on the gas system to help with dwell time & reliability. The funny thing is that an XM177E2 has about the same length as a 14.5" barrel, when the length of the moderator is included.
I've owned at least 3 different AR15's with 11.5" barrels, and never had a hiccup with them that I can remember. For a PDW, I would think of a physical profile objective of being a great under-the-coat gun.
LRRPF52
That 10.25" barrel CQBR upper is a SOCOM project that is meant to reduce the M4 profile for Close Quarter Battle, especially when used with a suppressor. If you look at the shoulder patch of the dude in the picture carrying the CQBR upper-equipped M4, it says it all.
That gas system and barrel length are more problematic with the AR15, even with a gas port diameter of .093". I have a friend who's waiting on a broken shell extractor right now for his. The Army learned this back in the 1960's with the 10" barreled XM177E1, before increasing the barrel length to 11.5" on the XM177E2, as well as using the moderator with baffles to increase back pressure on the gas system to help with dwell time & reliability. The funny thing is that an XM177E2 has about the same length as a 14.5" barrel, when the length of the moderator is included.
I've owned at least 3 different AR15's with 11.5" barrels, and never had a hiccup with them that I can remember. For a PDW, I would think of a physical profile objective of being a great under-the-coat gun.
LRRPF52