Subsonic Ammo

[Gadsden]

For educational purposes they both run off of gas but how that gas is used is different.

Direct impingement is the vast majority of ARs and gas piston is used on some but they still utilize gas just in different ways to move the bolt carrier.

Laying out your exact setup would be greatly beneficial in helping with suggestions. I honestly do not know much about the gas piston systems on ARs but if I had to guess there are definitely differences between them and that information will help someone who is more familiar with that exact system and helping you diagnose your issue.

Thank you, I'm still learning so I appreciate the information.

 

[PBramble]

First thing I'd do is get an adjustable gas block. Follow the procedure for it. It it still has issues, look into different buffers. One step at a time.

 

[Profreedomokie]

Okay my 308 is a bolt gun, but it's a 1 in 11 twist rate. My AR on the other hand has a 1 in 7 twist and is piston operated. So if I understand you I may need a different recoil spring so it will cycle correctly?

I don't have any experience trying to load a .223/5.56 subsonic. I would try the 77 gr. bullets, a 9mm recoil spring, and work up a load that just makes it cycle 100%. This should be done with a suppressor attached for the back pressure. An adjustable gas block might help also.

 

[PBramble]

I don't have any experience trying to load a .223/5.56 subsonic. I would try the 77 gr. bullets, a 9mm recoil spring, and work up a load that just makes it cycle 100%. This should be done with a suppressor attached for the back pressure. An adjustable gas block might help also.

good way to get baffle strikes if the bullet isnt stabilized.

 

[Profreedomokie]

good way to get baffle strikes if the bullet isnt stabilized.

I don't know that a bullet can be that unstable that close to the muzzle. I did similar experiments when I built my 300 Whisper without any baffle damage.

 

[HiredHand]

Just a quick read about subsonic 223 Remington ammunition is that it isn’t meant to cycle a semi-automatic rifle.

 

[Okie4570]

The only thing I subsonic load for is a .300blk in a bolt gun. And it is possible to load low enough to where the bullet doesn't exit the barrel lol. Learned that on the first day.

 

[Gadsden]

The only thing I subsonic load for is a .300blk in a bolt gun. And it is possible to load low enough to where the bullet doesn't exit the barrel lol. Learned that on the first day.

That's a lesson I hope I never have to learn..

It may be time for another gun or maybe a 300 blackout upper for mine IF I can talk my wife into letting me get one. She's on a remodeling kick right now so it's probably not going to be an easy sell.

 

[Okie4570]

That's a lesson I hope I never have to learn..

It may be time for another gun or maybe a bolt upper for the 223 IF I can talk my wife into letting me get one. She's on a remodeling kick right now so it's probably not going to be an easy sell.

If you're working up loads and your chrony reads all zeros, don't just assume that it was a malfunction. When I saw mine read all zeros I wanted to check the barrel, I cracked the bolt open to remove it and could hear the gas escape lol, pulled the bolt and looked through the chamber and sure enough the bullet didn't clear.

 

[leemozoid]

I have a couple questions on the subject

1) I have some subsonic ammo for my AR, but the rifle won't cycle when I'm shooting them. Any idea what the problem is and how I can fix it?

2) Where can I find the information on how to hand load subsonic ammo, specifically for 223 and 308?

Can't help with #2 but the answer to #1 is you can't fix it. The military tested subs in 5.56 for years and none would cycle the AR. This is one of the reasons .300 Blackout was developed for the AR platform. it can reliably cycle an AR style rifle in subsonic loads.