The New Daniel Defense MK18 barrels are ported at .072, and if you already have one of the overgassed barrels, Daniel Defense will replace the over gassed barrel with a .072 barrel.
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The New Daniel Defense MK18 barrels are ported at .072, and if you already have one of the overgassed barrels, Daniel Defense will replace the over gassed barrel with a .072 barrel.
I have two generally unmodified DD Mk 18s purchased in 2015. Both have ~ 700 rounds of exclusively high quality mil-spec ammo run through them. They have been run suppressed with Surefire SOCOM Mini 5.56 suppressors. I'm assuming I have the standard oversized gas ports.
My experience has been no detectable gas blowback for these 1400 rds over the two Mk 18s. And that's firing hundreds of rounds at a time at carbine courses, where other people with different suppressed carbines (16" of all types) were sporting black powder mustaches on their faces / wiping their eyes throughout the day.
FWIW, this problem appears to be fully solvable by running a Surefire SOCOM 5.56 suppressor. These were engineered specifically for the Mk 18 platform to drastically reduce gas blowback, which is a major reason they won the govt contract to supply suppressors (to mil or LE or both - not sure) for the Mk 18.
Given the above, would there be any reason for me to consider swapping barrels for a smaller port size? I don't know what it would be. As an aside, I ran all these rounds using the standard factory spring and H buffer. I've since put H2's in both, as I was told it should cycle more reliably if I slowed it down, but I just went 1 step heavier, as it already worked perfectly with the H buffers running Federal XM855 and M193.