I’m wondering if there are any operating/design parameters in place for mid-length gas 5.56 carbines. Things like gas pressure at port/port size, dwell time, buffer weight, etc. What is the sweet spot for the most reliable functioning?
My issued patrol carbine is a Colt 6520. I’d like to explore the possibility with my agency of modifying this weapon with a mid-length, 16", flat-top upper. I don’t want to broach this subject without being certain that weapons thus modified would not have diminished reliability.
Since there’s no real standard for midlength there isn’t a ‘mil-spec’ or NATO standard for gas port size etc. and you’re wanting to explore midlength for duty use I’d highly recommend using a BCM hammer forged or Daniel Defense hammer forged midlength barrel for best reliability. There are others who make good midlength barrels but are harder to get or are really just match barrels and not for your intended purpose. I’d recommend against some of the lower quality barrels vs. just staying with your Colt 6520 barrel.
Thanks. I’m already leaning towards a factory-built BCM BFH or Daniel Defense upper, so we’re on the same page there. I may wait until the LW-barreled uppers are available.