Subsonic .223 in my AR-15

[Ian]

I think I have a winner, third try.

Working with the Lee 224-55 bullet cast from basically WW alloy, sized .225" with one very light coat of Ben's Liquid Lube before and after. NO gas check. Brass FL sized and expanded to basically .224" or a tenth under. Left a .256" bellmouth which gets knocked back to .250" in the seating die, chamber neck is .252"-ish in the middle. Mixed bag of odd SR primers (tula, win, cci).

1.5 grains Hodgdon Titegroup = 830-ish fps
2.0 " " " = 890-ish fps
2.5 " " " = 960-iiiiiish, only got one to read and the others were compensated so not really valid. Good news is the 2.5 grain load closed 5-shot groups from 1" to 3/8" at 15 yards, so I think I'm done with load development except to buy a two-banger version of this mould, plain-base it, and HP one cavity.

The 2.5 grain load was starting to clink the bolt carrier against the buffer weight which to me as the shooter sounded just a little louder than the hammer strike. I may pull the buffer retaining plunger and spring out of the lower to take up the gap. Both hammer strike and bolt/buffer clink were louder than the report through my 30-caliber suppressor, and bullet impacting very damp dirt at 15 yards noticeably louder than both. My 35 YO Daisy one-pump pellet/bb rifle makes pretty much the same sound, I shot them side-by-side with pellets in the Daisy just to see.

One bonus is I didn't have to resize the brass after the first go. All that was required was change the primer, charge the case, and seat a bullet.

I have yet to take the rifle down and inspect the bore and gas system, but I will. Seems that so far the 1-in-7" twist was a good choice for this build, hopefully it will do well with heavy jacketed bullets too.

 

[KHornet]

Most interesting. Keep us posted!

 

[Ian]

What I'm trying to accomplish here is a short-range, movie-quiet varmint-getter that uses a reloadable, cheap, widely-available cartridge. Target-velocity and "subsonic" boutique .22 rimfire is expensive and sometimes hard to get, and the other option of an integrally suppressed rifle barrel for a 10-22 or 77-22 that would knock down high-velocity bulk ammo to 1K fps was expensive and honestly, not as effective as 55 to 80 grains of home-cast goodness out of a .223 case. I did look at the .22 TCM and decided Titegroup would probably make the smaller case irrelevant vs. the .223 case. I was right.

It also looks like gas checks will be unnecessary.

I almost bought an NEF .22 Hornet off the rack new at my LGS last week, but remembered the super-slow twist rate. They also had at least ten birch-stocked .223s there, all new and collecting lots of dust on a bottom rack. $309 was a little rich for my blood though, considering I'd have to have the barrel cut and threaded to suit my tastes. So instead I saved a bunch of money by spending $875 to put together an AR just the way I wanted it (and it still has a bargain-bin carbine buffer tube kit, upper receiver, barrel, lower parts kit, and Chinese/Amazon AAC copy 12" keymod handguard). At least I have a virtually silent repeater with my choice of magazines up to 100 round capacity....and didn't have to pay extra to have the barrel threaded for my suppressor-mount muzzle brake. Plus I can shoot all the regular 5.56 NATO and .223 Remington stuff in it, too.

 

[Josh]

I think I still have a 4 cavity 75 gr mould, it weighs in somewhere around 77 gr, I may have to heat it up for the first time. Following with interest.

 

[Kevin Stenberg]

Ian did you do a writeup on the 2 previous attempts?
I am confused (nothing new) Did you take the buffer & spring out of the stock and fire the gun that way?

 

[JWFilips]

Ian,
FWIW; I shrunk my subsonic groups in my .223 bolt rifle (55 gr CBE bullet and Bullseye powder) by switching from cci small rifle primers to Winchester small pistol primers.
I was pretty surprised at the results. I still need to do more testing with these light loads but I'm definitely going to keep trying the SPP to see if that was the real magic
Jim

 

[Ian]

Kevin, that was all three attempts, all I changed was powder charge and after the first loading didn't resize the cases. The very first try was acceptable, I just wanted to make sure the bullet exited the barrel and it did just fine. After that I put the chronograph on it and worked up to a good balance of accuracy, velocity, and noise. I didn't take the buffer or spring out because I didn't want to struggle with getting every round chambered for the test

Josh, I'm thinking 70-80 grains would really be the berries. Right now I'm basically duplicating Aguila 60-grain .22 LR loads and would like to do a little more.

 

[Ian]

Ian,
FWIW; I shrunk my subsonic groups in my .223 bolt rifle (55 gr CBE bullet and Bullseye powder) by switching from cci small rifle primers to Winchester small pistol primers.
I was pretty surprised at the results. I still need to do more testing with these light loads but I'm definitely going to keep trying the SPP to see if that was the real magic
Jim

I wondered about that. With my .308 and heavy bullets I found the balance of brisance with standard rifle primers. Magnum primers gave erratic velocities and terrible grouping, same with standard LPP. I have a whole bunch of Remington 1-1/2 primers and some others that could get used for this. I'll test them, too.

 

[Hawk]

Watching this with great interest.
I posed the question about subsonic loads on the CB website once and got all kinds of flack from a few members (why do you want to make a semi auto into a single shot, etc.).
In addition to the rim fire comments posted by Ian, I'm also looking at this from a survival stance.
I'm not a prepper, but in the hills, a few pounds of lead, a pound of power and a block of primers sure would go a long way if the SHTF.
Meat for the pot without attracting too much attention.
I'm thinking a heavier bullet, one that will stabilize in a 1-8" or 9" barrel at around 1,000 fps, would pack more punch and be easier to get consistent ignition. Maybe even cycle the action, though that is not a requirement.

 

[Josh]

I am going to have to dig around my moulds, it would appear I have cast this bullet before.

 

[Ian]

Watching this with great interest.
I posed the question about subsonic loads on the CB website once and got all kinds of flack from a few members (why do you want to make a semi auto into a single shot, etc.).
In addition to the rim fire comments posted by Ian, I'm also looking at this from a survival stance.
I'm not a prepper, but in the hills, a few pounds of lead, a pound of power and a block of primers sure would go a long way if the SHTF.
Meat for the pot without attracting too much attention.
I'm thinking a heavier bullet, one that will stabilize in a 1-8" or 9" barrel at around 1,000 fps, would pack more punch and be easier to get consistent ignition. Maybe even cycle the action, though that is not a requirement.

It would take some heavy modifications to get any weight subsonic cast to cycle in an AR-variant rifle. I like these because they don't pogo the bolt out of battery and smut the works.....particularly since I'm using a suppressor. I have over 40 rounds through it now and it's clean as a bolt-action.

Subsonic cast .223 in an AR-variant rifle can be a LOT better than .22 rimfire. First off, it's a repeater, not a single-shot, and it's magazine fed so you can load a whole whole bunch of those little pills in there. Second, it's not a .22 Rimfire from a either a ballistic standpoint or a terminal one. Even with what I'm loading it's 20 more grains of lead than most any other .22 Rimfire, with room to grow. You can also load jacketed bullets coated with a waxy lube like Ben's or straight LLA and shoot those if you need penetration. I want to go at least 75 grains. I did order another Lee mould today, this time a 2-banger and hopefully it has the new style blocks so I can easily install a traditional HP pin in one cavity and also drill out the gas check shank in both of them.

 

[Hawk]

Correct on the repeater. Just pull the bolt and chamber another round form the 30 in the mag.
Another advantage is the reliability of primer fired versus rim fired.
I'm constantly amazed to find so many rim fires lying on the ground at the range with striker marks on the rim. Had a few misfires of my own.
I've never had a misfire from a primer in my 35 years of reloading. Didn't have powder in a .38 Spl. once, but that was not the primers fault.

 

[Ian]

Got the Lee two-banger plain-based tonight, Ben-style. Not perfect but close enough I hope. Maybe Thursday I'll get some cast up and see.

 

[KHornet]

Keep us posted on your progress Ian!

 

[Ian]

Will do. My boss and I took turns with it yesterday at lunch busting clods on the hillside behind the shop at about 75-80 yards offhand, seems to be pretty accurate with the non-checked, BLL-coated bullets just like they are. I have to wonder if plain-basing them might be a mistake. If it is, I'm only out 20 bucks and still have the six-cavity mould that works like a charm. I'm going to hold off on hollow-pointing one of the cavities in the two-cavity until I see how the PB modification works out. The bullets that I've recovered so far are deforming pretty well (air-cooled wheel weights with a little tin added) so an HP might actually be a step backwards for head-shots on varmints.

I'm pretty astonished how well this little project is working out already. Case prep during load development was sloppy at best, necks off-center, seating die not seating bullets particularly straight, variance in neck tension, etc., but it shoots straight anyway! Low velocity is very forgiving of these sins.

 

[Josh]

I found some data on the 75 gr RN's I tried shooting these in my 222, even with max loads my 1-14 twist *just* wouldn't stabilize these bullets. I switched to the MX-2 55 gr bullet and it seemed to shoot well in the 1800 fps neighborhood.

I am going to have to try some of these 55's at low speed, the house I just bought is a bit further away from my range and I can't shoot full power loads there. Do you think a 1-14 twist will stabilize a 55 gr bullet at 1050 fps?

 

[Ian]

I really don't know. The only thing I have to go on is the Hornet guys say subsonic is pretty much a no-go with 1-in-16" twists.

 

[L1A1Rocker]

Enjoyed shooting it yesterday. VERY quiet! There's a real "giggle factor" when you get into the "stupid quiet" territory.

 

[KHornet]

"Stupid Quiet" territory! Ya just gota like that term!!!

 

[KHornet]

Ian, I have the 37gr. NOE for both GC and PB. If you would like to try some of them let me know and I will send some.
Paul