Originally Posted by
cacop
I have a few questions.
The fellow over at 03designgroup has mentioned he has cut his carbine gas system rifles down to 14.5 and his middys at 16 so they have the same length of barrel forward of the gas port. Is this the key to the middy vs. carbine debate?
Also vuurwapen blog mentioned how Colt's 16 carbine gas system guns had bigger gas holes in the barrels than their 14.5 counterparts. Is this something we need to account for, gas hole size?
I remember Ken Elmore before he left Colt in my AR-15 armorer's course discussing the gas system at the end of class. He wrote up on the board some thing like this:
__________A_____________/\_______B___
A being the part of the barrel before the gas hole.
/\ being the gas hole.
B being the part of the barrel forward of the gas hole.
Ken said if you change one of those you have to change the others otherwise you are going to have problems. It was part of his warning to us not to cut barrels down without having someone do it who really understood how changing one changed the others. He was really talking about changing B. He pointed out that the Commando, M4, and M16 gas ports went big, small, and big. Commando was big because it needed gas now, M4 small because it had time with a longer B, and M16 big again because it needed more gas for the long A.
The question I have besides the one above is how does changing A 2 inches forward in a 16 inch gun affect /\. Does /\ need to be bigger or smaller? What about taking a 16 carbine and cutting 1.5 inches off of B?