opening up gas port
- Thread starter HT308
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jlindholm70
New member
I don't know how much experience you have with trying to run sub-sonic loads, but from what I've found with my LAR-8 in 308, getting a sub-sonic load to cycle in a gas gun is going to be next to impossible. I run a 180 grain round nose (round nose to keep the length down so the likelyhood of a baffle strike is minimized) bullet in a 1/10 twist 308 barrel with around 10gr of Trailboss. It's very quiet, and a cool demonstration for friends to show how quiet it is, but it turns my LAR into a single shot. Doesn't come close to cycling the action.
In order to keep your velocity below 1000 fps, the bullet will have to be very heavy. I have a Noveske adjustable gas block on my 18" AR-15 and trying to get a heavy enough bullet with a fast enough twist to avoid a baffle strike is dicey at best. I imagine if you run a 10" or less barrel with Trailboss powder and a 80 plus grain bullet, you may stay below 1000fps, but I highly doubt it will cycle the action, regardless of how big you drill out the gas port. It seems to me that you're going to be risking a baffle strike and ruining a perfectly good suppressor, as well as having a barrel that has been drilled out and is no use for normal ammo.
The 5.56 is not a good option for sub-sonic ammo and I'd do a lot more research somewhere other than a board like this for a solution for the work you want done.
In order to keep your velocity below 1000 fps, the bullet will have to be very heavy. I have a Noveske adjustable gas block on my 18" AR-15 and trying to get a heavy enough bullet with a fast enough twist to avoid a baffle strike is dicey at best. I imagine if you run a 10" or less barrel with Trailboss powder and a 80 plus grain bullet, you may stay below 1000fps, but I highly doubt it will cycle the action, regardless of how big you drill out the gas port. It seems to me that you're going to be risking a baffle strike and ruining a perfectly good suppressor, as well as having a barrel that has been drilled out and is no use for normal ammo.
The 5.56 is not a good option for sub-sonic ammo and I'd do a lot more research somewhere other than a board like this for a solution for the work you want done.
svt tactical
Active member
If you wanna run a suppressed AR look at the 300 AAC blackout or equivalent round.
Silenced America
New member
jlindholm70 is right. Running 5.56 subs is just a bad idea, at best. .308 subs will not cycle the action, but they are stupid quiet. The .300 Blackout is a good cartridge to suppress if you want to run subs in an AR platform and have if function as intended. It is basically just a barrel change. You could build an upper and have it standing by. I have seen sub loads for the .300Blk from 175 grain to 220s. Supers from 110 grain. The parent case is a 5.56, so your standard AR mags work, The same BCG works. It is just the barrel.
When you suppress a 5.56/.223, you are basically getting a the same performance you would get out of a .22lr. There is not really a point.
When you suppress a 5.56/.223, you are basically getting a the same performance you would get out of a .22lr. There is not really a point.
Evil_Lurker
New member
Quote:When you suppress a 5.56/.223, you are basically getting a the same performance you would get out of a .22lr. There is not really a point.
Yep. You can build a 10-22 that fuctions reliably, gives the same performance and likely shoots more accurately and cheaper than an AR platform.
If you could build an AR upper that could shoot both standard and sub-sonic ammo I'd see the attraction, but I seriously doubt you're going to work that out. Too much buffer spring tension to handle the full power loads and still get it to function with the subsonic ones.
Why don't you just go with a 22LR adapter kit and feed it subsonic 22LR? Some of those seem to work pretty well.
Yep. You can build a 10-22 that fuctions reliably, gives the same performance and likely shoots more accurately and cheaper than an AR platform.
If you could build an AR upper that could shoot both standard and sub-sonic ammo I'd see the attraction, but I seriously doubt you're going to work that out. Too much buffer spring tension to handle the full power loads and still get it to function with the subsonic ones.
Why don't you just go with a 22LR adapter kit and feed it subsonic 22LR? Some of those seem to work pretty well.
JoeBobOutfitters
New member
Stick with supersonic 223 or 300BLK. The nice thing about the 300 is you can use 223 brass to make it if you want, or buy off the shelf brass. We've been tweaking some pistol/carbine gas length uppers and can get them to cycle both subsonic factory Remington loads and supersonic handloads using an adjustable gas block and no other modifications. That's about the only caliber that's been mainstreamed to be able to run subsonics reliably in an AR platform.
You can also run a 9MM can on a 300BLK with subsonics only if you want.
You can also run a 9MM can on a 300BLK with subsonics only if you want.