AR Sponsor
Posted: 8/30/2009 3:28:34 PM EDT
|
I'm trying to find the difference between the BCM Standard 16" M4 Carbine Upper Receiver Group (http://www.bravocompanyusa.com/BCM-M4-16-Upper-Receiver-Group-p/bcm-urg-m4-16.htm)
and the BCM Stardard 16" Mid Length Upper Receiver Group (http://www.bravocompanyusa.com/BCM-16-Mid-Length-Upper-Receiver-Group-p/bcm-urg-mid-16.htm). It seems that the M4 is out of stock and boasts "Mil-Spec 11595E - 4150 Grade Barrel Steel (CMV)" but the standard is the exact same except for "Mil-Spec 11595E - Barrel Steel (CMV) " and its in stock Any other differences? |
|
Thanks guys.
Upon searching for the differences between a carbine and mid length gas system, I came up with posts that are way over my head. Anyone have a good quick and dirty rundown on carbine vs. mid length gas systems for a 16" barrel? Specifically for the two that I posted? |
|
When you fire, the bullet passes a hole in the top of the barrel about halfway down that sends gas upwards into a block and then down a tube back into the gun and blows that bolt backwards. That is what makes your brass eject and then the spring pushes forward and puts another bullet in so you can fire again.
That is the "Gas System" So on a carbine length gas system the hole is only so many inches down the barrel. On a mid length gas system, the hole is further down the barrel (toward the muzzle) than it is on the carbine length system. There is another "rifle length" gas system that is further still down a barrel and it is usually on 20" barrels or so. With a gas system that is further down the barrel, say the mid length, you will need a longer gas tube and longer hand guards / rail to get to the gas block. |
|
Many people like the mid-length system because they feel the recoil impulse is a little bit smoother, due to the fact that the gas port is further down the barrel. This results in less gas pressure at the port at 9" down the barrel (mid-length) than there is with a carbine system at 7" down the barrel. I've heard some claim better reliability with the mid-length system as well.
As an aside, I just got a mid-length upper from BCM, and just finished putting it together with an RRA lower I've had in my safe for several years. The materials and finish on the upper are TOP NOTCH, and Bravo Company is an awesome company to deal with. I buy whatever I can from them, and highly recommend them. |
AR Sponsor