Has anyone tried loading 223 subs?

[okie]

I've seen there are a few manufacturers who are successfully producing 223 subs that don't squib and actually seem to cycle. I was wondering how they are doing it, and how a home loader might be able to replicate it. Are they using some kind of filler to take up the extra case volume, or are they using a powder that just takes up that much space?

[ViniVidivici]

I can't imagine a more pointless reloading endeavor.

[okie]

I can't imagine a more pointless reloading endeavor.

Maybe I want to shoot my Mk18 without hearing pro when practicing at close range. Maybe I might like to do some night shooting with the nods without the neighbors calling in noise complaints from two sections over in the next county.

[1168]

I put some thought into this a while back, and decided not to mess with it. I tried Atomic “Cycling Subsonic”. It was like 102gr, but it keyholed badly in my 1/7 12.3”. It definitely didn’t cycle, either, but I didn’t try it with the can. DocSherm said he had success with their ammo.

Speer makes a heavy RNSP. I wonder if that might be a good projectile choice. Maybe you could try Trailboss with pillow guts.

[308sako]

Yes and quiet is possible, but no cycling in my attempts.

[Ready.Fire.Aim]

I do a lot of subsonic reloading. Such as 300Blck, 9mm, .458SOCOM, .308, .44 special, etc.

Mostly bolt action but have AR15 set up specifically for subsonic in .300black, 9mm, .45acp, and .458.

I never tried loading subsonic .223 for an AR15.
But if I did, I would use a heavy ( long) bullet like a 77 grain, pistol powder like H110 with filler, and preferably an adjustable gas regulator. I would experiment with lighter buffer weights. Possibly a silencer to add backpressure.

I would expect a lot of failure to cycle, failure to feed.
Also bullet keyholing.

Good luck and please update if you find a workable solution.

[ViniVidivici]

It would be easier just to get a .22 conversion.

[okie]

It would be easier just to get a .22 conversion.

Have one, but it's not the same. And they get the rifle FILTHY! I mean failed trigger resets within 200 rounds kind of filthy, and it schmoos up the gas tube and everything, too.

[okie]

I put some thought into this a while back, and decided not to mess with it. I tried Atomic “Cycling Subsonic”. It was like 102gr, but it keyholed badly in my 1/7 12.3”. It definitely didn’t cycle, either, but I didn’t try it with the can. DocSherm said he had success with their ammo.

Speer makes a heavy RNSP. I wonder if that might be a good projectile choice. Maybe you could try Trailboss with pillow guts.

Keyholling would be fine. I just want to shoot steel inside 50 yards.

How do they load such a heavy projectile? I didn't think it was even possible.

[okie]

Yes and quiet is possible, but no cycling in my attempts.

Were squibs a problem? Did you use some kind of fill to take up case volume?

I was thinking about the cycling thing, maybe I could try using a super light buffer, spring, and aluminum carrier. That's no more commitment than using my .22 conversion, and it wouldn't get things so dirty.