Mid-length gas system in the cold.

[Gargoyle]

The most functional and precise AR platform ejects brass to the 2:30 clean, and then to the 3:00 dirty. Past 3:00 is inviting problems. I believe Superlative Arms is the one to thank for civilians thinking 3:30 is optimum.

[Caduceus]

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.

Um.... wouldn't 180 degrees be shooting your own shoulder....?

FWIW, having shot in -20, no real issues, but limited to 2 carbines. And I haven't tried straight down, but with several new deer stands in new property, I'll be glad to try this winter.

[mr h]

when i do lock back function tests its with the weakest ammo i have and then hold the rifle by the pistol grip only. if it passes that, i figure gtg but will be trying this vertical thing out.

anyone have gas port size info on a 12.5” midlength?

i’ve been experiencing random bolt over stoppage with wolf gold and ppu ammo only, suppressed and non-suppressed.

not with imi 193 and razor, xm193, gold dots though.

.080” port size, as measured with a machinist bit. it was a FN 16” to start with.

it’ll lock back with that ammo though.

[mig1nc]

when i do lock back function tests its with the weakest ammo i have and then hold the rifle by the pistol grip only. if it passes that, i figure gtg but will be trying this vertical thing out.

anyone have gas port size info on a 12.5” midlength?

i’ve been experiencing random bolt over stoppage with wolf gold and ppu ammo only, suppressed and non-suppressed.

not with imi 193 and razor, xm193, gold dots though.

.080” port size, as measured with a machinist bit. it was a FN 16” to start with.

it’ll lock back with that ammo though.

I’m also working on a dedicated suppressed 12.5 middy that might get used in the cold. If anybody has a good gas port size suggestion for that I’d also like to hear.

Mine is cut down as well. Although the marks are gone so I can’t tell other than it was chrome lined and M4 profile.


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[mr h]

I’m also working on a dedicated suppressed 12.5 middy that might get used in the cold. If anybody has a good gas port size suggestion for that I’d also like to hear.

Mine is cut down as well. Although the marks are gone so I can’t tell other than it was chrome lined and M4 profile.


Sent from my iPhone using Tapatalk Pro

i feel like i am out running the mag, since it’ll lock back. ejection is 1-2 oclock.

this barrel has seen 4-5000 rounds so maybe i have port erosion and its bigger inside.

also need to try new mags. the ones i’m using are from my bin of daily wear mags so they to have alot of use on them

its been years since i ran a can on this and dont recall issues then but i am getting old….

[davidjinks]

I’ve run my DD V7 with H2 and H3 buffers in the winter 20-30° and never had issues. My lock back tests are with 2 of the worst mags I have in the same manner, shooting 1 handed with no shoulder, and it locks back every time. Of course, I don’t live in Alaska anymore so -50° testing won’t be completed.