Good Comparison of Different Barrel Lengths

[prepare]

10.3, 11.5, 12.5. 13.7, 14.5, & 16 velocity differences and bullet drop at 300 yards.

[dpb1776]

That was a good episode, didn’t learn anything really I didn’t know. But watching the grouping on targets was cool.


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[prepare]

Out of all the barrels the largest velocity gain was between the 10.5 and the 11.5.

I agree with his conclusion that 11.5" for a short barrel and a 16" for a non short barrel make the most sense in terms of performance.

I always found it odd that the mil chose the lower performing 10.3 Mk18 over an 11.5

[Dutch110]

Out of all the barrels the largest velocity gain was between the 10.5 and the 11.5.

I agree with his conclusion that 11.5" for a short barrel and a 16" for a non short barrel make the most sense in terms of performance.

I always found it odd that the mil chose the lower performing 10.3 Mk18 over an 11.5

I've got both so no dog in this hunt. But my guess is the shorter barrel once you add a can and using it for CQB/Room Clearing duties played into the decision. More maneuverable. But honestly I cant tell a difference in handling between my 10.5 and 11.5. I do have an unnatural love for my 10.5 for some reason.

[markm]

I do have an unnatural love for my 10.5 for some reason.

I went through that phase for a while. But at some point the thunderous report started wearing on me. And suppressors just suck on ARs... especially shorties.

I'm breaking it back out though because I put one of the B&T Quad rails on and am dying to shoot it.

[Todd.K]

I went through that phase for a while. But at some point the thunderous report started wearing on me. And suppressors just suck on ARs... especially shorties.

Just get the gas turned way down and make it dedicated for suppressed use.

[Dutch110]

I went through that phase for a while. But at some point the thunderous report started wearing on me. And suppressors just suck on ARs... especially shorties.

I'm breaking it back out though because I put one of the B&T Quad rails on and am dying to shoot it.

I picked up an Otter Creek Labs Polonium a few months back. It's still in jail at my LGS but they have an indoor range so conjugal visits. That can makes my 10.5 fun to shoot. I cant wait to get it outside. I have a Colt 10.5 that was a crane chop from 14.5. No idea what the port size is but with an A5H2 and the can its pretty awesome. I've only shot it twice now but each time people stop by to ask what can I am using because they can't believe how quiet it is on a 10.5. But yeah, without a can it sucks.

[georgeib]

Just get the gas turned way down and make it dedicated for suppressed use.

That's what I've done with one of my 11.5s. Was initially running it with a direct thread mount with the Turbo K, but switched to a JMac 360 brake/direct thread adapter to protect the blast baffle. Only time the can comes off is when I'm doing a thorough cleaning. Running a .057 BRT gas tube and an A5H2, rifle runs great with even steel cased and will barely lock back.

No, it's not something I'd exactly call quiet, but it's manageable even without hearing pro for a few rounds. This is primarily an HD weapon, and even with the can, it's still shorter than a 16" and way way quieter than the 16 without a can.

[Disciple]

Out of all the barrels the largest velocity gain was between the 10.5 and the 11.5.

Caveat: with those particular barrels and ammunition. A cut-down test is more accurate. Obviously there is a trend of greater velocity loss with each inch cut but there is no universal threshold across ammunition types where it suddenly falls.

[C-grunt]

I always found it odd that the mil chose the lower performing 10.3 Mk18 over an 11.5

I read a while back that the Mk18 is a 10.3 because the Navy was specifically looking to go as a short as possible for on ship operations.

The new Mk18 with the Geiselle rail (still called the Mk18??) has an 11.5 inch barrel.