I am new to the AR world but I recently purchased a PSA AR10 .308 caliber. And it doesn’t wanna cycle subsonic rnds.. I’ve been reading forums and trying to find the right ammo or mods to do without spending a arm and a leg. All suggestion are helpful just trying to figure this out. Thanks

Why did you buy a .308 to shoot subs?

The short answer is that it's not gonna cycle subs without substantial modifications, if at all. 300 Blk uses pistol length gas for a reason, and with .308, you're increasing bolt weight significantly, which compounds the issue. You could try loading with 240 gr. Woodleighs or Sierras and opening up the gas port, but I don't think you'll get sub loads with enough gas volume & pressure to cycle an unmodified middy gas .308 unless you start swaging very heavy bullets.

I have only ever heard of one instance of an AR-10 cycling subs. The author claimed to have a recipe that worked with his POF 308 but when pressed for details he was never heard from again.

I have always wondered if it might be possible to get an AR-10 to cycle subs with a pistol length gas system and an aggressive gas port in the barrel and probably a reduced tension buffer spring and maybe a light bolt carrier group but I've never had the time, money or inclination to pursue it.

It's apparently possible to get a FAL to cycle subsonics, but takes a lot of work getting it there.

Partial weld over the gas setting, proper powder selection.

But it has been done with a 308 AR.

https://www.youtube.com/watch?v=rYGrAsCRWTs

John A. wrote:It's apparently possible to get a FAL to cycle subsonics, but takes a lot of work getting it there.

Partial weld over the gas setting, proper powder selection.

But it has been done with a 308 AR.

https://www.youtube.com/watch?v=rYGrAsCRWTs

That's the guy from years ago.

Did he ever publish a how to?

Probably best to not mess up a good, functioning .308 and instead trade for or buy a 300 Blackout AR 15.

If it were me I would save the AR 10 and build a quality 300 Blk from parts. There are plenty of "how to" videos and books out there. A very rewarding experience. Then get yourself a suppressor.

Agreed with above... If you want a subsonic 308... build/buy a 300BLK. Save the 308 for supers.

JW

If your 308 were modified enough to cycle subs it would most likely be way over-gassed with full power .308 and would beat itself to death.

Without a can, subs are not worth the aggravation.

On the plus side, now you have a .308 that will be more enjoyable to shoot.