Mid-length gas system in the cold.

[Disciple]

sinister, I don't understand the intent of your post. In clarification, what is your opinion on mid-length vs carbine-length gas systems for 14.5" or 16" barrels?

[sinister]

Carbine-length has worked for a long, long time with 11.5, 12.5, and 14.5, and is way over-gassed for a 16-incher. Adding a suppressor over-gasses a 14.5.

A mid-length gas tube helps balance suppressed 14.5s, and 16"ers both unsuppressed and suppressed.

[prepare]

Obviously, a 14.5 with a 0.0625-0.0630 gas port will be up to military requirements . . .

But, most 16" mid-lengths I have will not reliably lock back when shot 180 degrees straight down, and these are the common available port sizes. That does not instill confidence if you start to factor in -20 degree performance.

What is shooting 180 degrees straight down testing for? Is it a test that is supposed to simulate something specific?

[prepare]

Carbine-length has worked for a long, long time with 11.5, 12.5, and 14.5, and is way over-gassed for a 16-incher. Adding a suppressor over-gasses a 14.5.

A mid-length gas tube helps balance suppressed 14.5s, and 16"ers both unsuppressed and suppressed.

The flow through cans seem to solve the gas issues in terms of have a properly gassed gun for both suppressed and unsuppressed. Not to mention they're healthier on the lungs.

[Uncas47]

What is shooting 180 degrees straight down testing for? Is it a test that is supposed to simulate something specific?

Yes it is, a three dimensional battlefield. Flat range is no bueno.

[1168]

As an aside, aren't some types of powder and primers more temperature sensitive than others?

yes. But, in my limited experience, the ones that are, are ones that also produce gas drive to spare. Hopefully someone smarter weighs in on this, since I rarely shoot below the -teens F*. Hell, I very rarely even shoot below the 30s F*, anymore.

What is shooting 180 degrees straight down testing for? Is it a test that is supposed to simulate something specific?

The weight of the reciprocating mass is working against the gun more than it would level with the deck. Basically creating a worst case scenario. With that said, I shoot nearly straight down fairly frequently, and it hasn’t been a problem for me with any gun that otherwise runs.

[prepare]

yes. But, in my limited experience, the ones that are, are ones that also produce gas drive to spare. Hopefully someone smarter weighs in on this, since I rarely shoot below the -teens F*. Hell, I very rarely even shoot below the 30s F*, anymore.



The weight of the reciprocating mass is working against the gun more than it would level with the deck. Basically creating a worst case scenario. With that said, I shoot nearly straight down fairly frequently, and it hasn’t been a problem for me with any gun that otherwise runs.

Thanks for the explanation.

How are you shooting nearly straight down... mountains, helos?

[1168]

Thanks for the explanation.

How are you shooting nearly straight down... mountains, helos?

Structures.

[sinister]

Obviously, a 14.5 with a 0.0625-0.0630 gas port will be up to military requirements . . .

But, most 16" mid-lengths I have will not reliably lock back when shot 180 degrees straight down, and these are the common available port sizes. That does not instill confidence if you start to factor in -20 degree performance.

A rifle or mid-length carbine that doesn't shoot straight up or down (suppressed or not) obviously isn't built correctly. I can't remember exactly, but H1 should be the correct buffer (and I've gone as heavy as H3, HSS, and XH).

Of course you shouldn't find that out if you're supporting others from a tower, high ground, or out the side of a helicopter -- same as uphill shots (i.e., from a street or valley at knuckleheads on high ground or rooftops).

A friend of mine (who was working at AWG at the time) and I linked up in Baghdad and as we caught up he asked, "Remember when we were kids and in the movies the good guys shot the bad guys and they fall two or three stories into the street?"

"Yeah, of course."

"Finally did it. Shot him from a Stryker."

[ViniVidivici]

HA! Right on.

Now I have something to try this winter.

Was shooting up at a fairly steep angle with a midlength just a couple weeks ago, no issue. 70ish degrees though. Can't remember last time I shot at a steep downward angle though. That'll change.

Another good thread with valuable info.