Best location for gas port hole vs. length in 18" barrels

AR/M4 AR Technical Discussion
1

From a recoil and velocity standpoint, what is the preferred location to drill the gas port in an 18" barrel? At rifle or Mid length and why?

2

door number three… “intermediate” length. see www.noveskerifleworks.com

as to why: rifle length generally shoots real smooth out of an 18", but the potential for short-stroking is increased… the bullet doesn’t spend enough time in the bore after passing the gas port to get pressures up high enough for my comfort level. with a mid-length, the bullet spends too much time in the bore after passing the gas port, leading to harsh cycling and durability issues. its probably, on the whole, more reliable than rifle, but neither is ideal.

so vltor and noveske collaborated to create a gas system specifically for 18" barrels. puts the port in the right spot for the best physics.

3

So we’re talking a gas tube length of 8.6875" and a gas port drill size of 0.0540" for the “Intermediate” length?

This may be a dumb question, but can one cut a rifle gas length tube and clean up the machining to make an Intermediate length tube? I’m assuming the “Intermediate” length tube is not commercially available at this time.

Also, what would be the best length rail for this gas tube length if one wishes to buy an off the shelf rail?

Thanks,

Dave

4

He’s right on the smooth shooting (and everything else). I have a 17.5" HBAR with rifle gas, and it barely moves. Of course, my new middy with a Spike’s ST-T2 buffer is pretty smooth too.