Subsonic .223

[kawasakifreak77]

I've got a YHM 7.62 phantom that is mostly dedicated to my blackout boltgun. I've also put an adapter on my Dad's AR. I noticed a few boxes of 77gr Hornady match bullets on the shelf... it would pretty much be a novelty, good for nothing but short range plinking & small game but who's made .223 subs here?

Dad really likes his AR (served in storm) & is really getting paranoid about losing anymore of his hearing. I'd like to make him so QUIET loads for his AR when we're out with my can. It makes shooting so much more enjoyable. I know they won't cycle. Will a 1-9 bareel stabalize the .224 heavies at 1000 fps?

Thanks for any help!

Edit: I have a chrony. So if someone just gets me close I can tweak the load myself. Hopefully a few grains of the Hercules flake powders will do it. I have red / green / bluedot already open & collecting dust. Have to save the precious bullseye & unique until I can find more!

[Artful]

I've used 4.3 gr of Trail Boss with 55 grainer for 950 fps but I don't know that 1:9 will stabilize 77's

you might start here
http://www.bergerbullets.com/twist-rate-calculator/
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
http://members.shaw.ca/cronhelm/SubsonicBullet.html
before putting your can on his rifle shoot them thru some cardboard up close to make sure not yawing

[303Guy]

Supersonic with a good suppressor is pretty quite in a 223. You could buy them and see and if they won't stabilize at the velocity you want then you could use them for full power loads for yourself. Hornady tends toward spire points, are these spire points? Spire points might be more stable than spitzers, I don't know but I do know my 16 twist hornet stabilized 63gr Hornady spire points perfectly (at around 2640 fps).

[Lonegun1894]

My AR is one of the Bushmaster 14.5" with the AK-74 muzzle-brake to bring it to 16", and is 1:9" ROT. I tried it without a can just to see how low I could go, and could not maintain stability at 50yds with a 75gr at anything slower than 2200 fps, and even that fell apart by the time it got to 100yds. Now a full power load keeps 77s stable in mine out to at least 900yds. A friend can't keep the same exact handload with the 77s stable at 100yds though, so each rifle is different. I'd say just try it without the can on it at your desired velocity, just in case it isn't stable, and see if it is stable at say 25yds. Worst case scenario, you find out it isn't stable and have to try a different load. And I mean it when I say to do the testing without the can so you don't get baffle strikes and damage your investment.

[kawasakifreak77]

I'm afraid they won't be stable. Just wish I could do something with all these bullets! Dad bought 'em originally thinking he wanted a heavy bullet for his 22-250 but it didn't take long to figure out that wasn't going to work..

Maybe I could trade into some pull down SS109s to keep my investment to a minumum here since after all, these will just be a novelty.

[Multigunner]

A .22 LR adapter, those with chamber extension and their own sleeved blowback bolt that replaces the bolt and carrier and .22 LR magazines, would serve the purpose better, though expensive they at least cycle in semi auto.
The conversion and reversal are fairly quick and don't require alterations to the rifle.

I'd be careful of stuck bullets with such a light load and jacketed bullets.

Not that down loaded cartridges are not a good idea, just that there are alternatives.

I wonder if the plastic bullet training rounds are available?

Theres also a compressed air conversion that uses .22 round ball. It feeds and cycles like the real deal.

[Tackleberry41]

You could try the bullets backwards and see how they do. Thats the way I have seen some loading sub sonics before. I messed with subs in an AR I had. It was 1-9, I could get 62gr FMJ to stabilize at that velocity, but nothing heavier. A flat based spitzer or something cast might go a little heavier. It was really quiet, but being a single shot weapon, just better to use a 22lr. You could get away with a much lighter 22lr can on an AR using subsonics, but one full power round and you wouldn't have it anymore.

[biffj]

You need to remember that at subsonic speeds the twist rate needs to be even faster to keep stable. This means you'd be stuck with lighter bullets just to keep them stable enough to avoid tumbling and possibly trashing your can. In real life you're much better off shooting a .22LR through the can. Its simpler and is probably as much or more energy than what you'd get out of your slowed down 223. Its a lot less trouble too.

Frank

[petroid]

If you look at subsonic 22LR ammo, the heaviest bullet I've seen is the Aguila SSS Sniper SubSonic at 60gr. Most say it needs a 1:9 or 1:11 twist rather than the standard 1:16. If you try bullet weights starting at 62gr and lower you will probably find a load that wil stabilize. The length in combination with the profile of the bullet is what determines RPMs necessary for stabilization. Push a long, heavy bullet fast enough out of a slow twist barrel and it will stabilize but it may need 6000fps lol. Spitzer bullets are longer per weight than RN bullets so you are limited in your bullet weight choices. Go light. Cheap 55 grainers will probably do just fine.

[kawasakifreak77]

Thanks for all the imput. There's no point in converting the rifle to .22 with as hard as the ammo is to get! My .22 is my least used rifle. 223 I can reload, .22 I cannot!

Currently I'm searching for some cheap jwords like ss109. Like I said it's just a novelty, something for my dad.

[kawasakifreak77]

Oh & I've suppressed the AR with full power loads, that is not quiet! It's quieter, for sure. Maybe even hearing safe, not sure.

But my blackout boltgun makes a .22 rifle seem loud. that's what I'm after here.

[allen16323]

Build him a 300blk upper can be done cheap and you are aparentely already set to load for it. Can be done pretty cheap if you bargain shop is and use blem parts, my 8" upper came in under 400, until I decided it needed a fancy free float handgaurd.