Poor results with .223 subsonic!!!

[husbandofaromanian]

I finally got some time from work to do something I have been wanting to do for a long time. Load subsonic .223. So I loaded some with varying weights to get a good charge. Then, I loaded 15 cartridges with said weight and went to the range.

.223 subsonic recipe:
Lapua case
federal 205 primer
Trailboss powder (5.6 grain)
Sierra 63-grain smp bullet (same as Engel's)
not crimped (no good reason why, just didn't do it)
powder measured with a gempro scale (.02 grain resolution)

Firearm:
TC Contender
mgm barrel 13" 1-7 twist
ss16 scope
shot off of a tripod on a bench
(same setup shoots 22lr 1moa)

Results:
Speed where all over the map. 1097 to 998.
Grouped about 1" at 50 yards

This is completely unacceptable to me. What can I do to get better velocity consistency and accuracy???

 

[kingmt]

Switch to a shorter bullet. It isn't going to stabilize that long of a bullet at that speed.

I can't offer much more info then that since I don't know that powder. Within 100 fps over all is pretty good. Were not talking about a slow powder that you have 25gn of. Think about this if you have a 2gn variance at 25gn that is 8% at 5.6gn 8% is only .5gn. So for every .1gn your off is like .5 with your slow burn.

 

[husbandofaromanian]

I already checked stability before screwing on my silencer (cardboard) My stability factor is a little more than 3 (very stable).

 

[SlowFuse]

What was cardboard?

 

[jmorris]

(card board) He was checking for keyholes, so he didn't get a baffle strike with the can on.

I might be short sighted but I never got the point of a SS .223 when it's pretty much the same as .22lr. In any case, trailboss while bulky has not been the best at holding a low SD. I don't like to post load data that you can't find in a book but you might search faster powders like VVN310 and 320. They should do better in the short barrel.

 

[bluetopper]

Use 40gr bullets......or yes, use a 22LR at a lot less expense.

 

[husbandofaromanian]

Every time I start a thread about suppressed .223, I get posts about 22lr. I have been shooting 22lr suppressed for 7 years. I can pop balloons at 300 yards easily. I went to .223 subsonic for these reasons.

1. Stop leading up my silencer.
2. Better bc
3. Ability to have control of the speed.
4. Better accuracy.

I still shoot a lot of suppressed 22lr so I did not trade one for the other.

 

[RedHeadHunter]

It looks like you have very little powder in your case. You may be getting inconsistent ignition of your powder. You can try using a slower powder to get more in the case, or use nylon pillow stuffing to keep the powder to the rear of the case. I don't know what the burnt pillow stuffing will do to your suppressor.

You might try the stuffing with out the suppressor to confirm if that improves your groups and go from there.

Good luck!

 

[husbandofaromanian]

I'm getting about a 70% case fill. If I use any other powder, the fill will be much, much less.

 

[husbandofaromanian]

Would crimping help with my velocity consistency? Would pushing the bullet deeper in the case help by increasing case fill percentage?

 

[kingmt]

I have never tried to crimp. I still think your bullets are to long for that speed. I have shot bullets backward & gotten better groups.

 

[greyling22]

this may be an exceedingly ignorant suggestion, but do you think a magnum primer might help get more consistent ignition?

 

[jmorris]

To stop leading is a good reason but if your already hitting ballons at 300 yards (assuming we are not talking about hot air ballons ) that would be hard to beat with the few loads I messed with. The better BC is also a false hope as at rainbow trajectorys a lot of the longer bullets prefer to fly backwards. You might try a few just to see if they group better than your current load.

 

[Toml]

You may as well accept the fact that you may not get the results you want at low velocity.

 

[Waywatcher]

I think you should stick with the Trail Boss; it's a safe and good choice for your application. I would, however, start trying different bullets and primers. I would go both ways, try some lighter bullets like 55, and try some of the heavyweights like 69, 75 and 77 grain. A quick run through a stability calculator looks like they should stabilize.

 

[the count]

Just using plain logic would mean that a lighter load also demand a much lighter bullet. A 55 grainer is not light, thats standard. I mean a 40 or 45... Some guys at my range that have been shooting for 40 years told me its almost a waste of time trying to get better accuracy with a sub sonic load. Do you know what shooting off the lands means? Now there you have a definite accuracy improvement if done correctly.

 

[husbandofaromanian]

but do you think a magnum primer might help get more consistent ignition?

That's a great idea. I think I'll try it. I am thinking now to combine a magnum primer with crimping the bullet. This may give the powder a chance to burn more before the bullet leaves the case.

 

[Ranb]

I had good luck with Speer 70 grain round nose bullets with H110 and standard small rifle primers. You do not need to fill the case if you use a fast powder. While a pistol powder like bullseye might work well, I have always used H110 (or WC820) in my subsonic rifle cartridges. I always have better accuracy with standard ammo then with subsonic ammo in guns/cartridges made for supersonic ammo.

Ranb

 

[husbandofaromanian]

Ranb, do you have a recipe for that cartridge? I am using fireformed Lapua cases. What primer and powder charge should I use?

 

[kingmt]

I never got good groups with Bullseye. None have been great any slower then 1500 fps but that is supersonic. I get 1" groups at 3000 fps in the .243 with a powder in the burn rate of Blue Dot. I know this isn't what your looking for just putting it out there. The crack of the powder is quite but you still get the supersonic crack.

 

[Ranb]

I used about 7 grains of H110 with a Winchester small rifle primer and a Speer 70 grain bullet. It was good for about 3 moa in my AR-15 with a 1-9 twist. You will need a chronograph to make sure the velocities are right.

Due to the much higher powder charge it will never be as quiet as subsonic 22lr with a silencer. But it beats the power of any 22lr by a wide margin.

Ranb

 

[husbandofaromanian]

I am getting 2moa right now and I am very upset with that. I get 1moa with 22lr.

 

[Ranb]

I suggest that you try a cartridge made for small charges of powder. My 22 K-hornet gave better results when loaded subsonic. Trying to make the 223 into something it was not intended to is probably going to lead to disappointing results.

My 300 whisper is designed for subsonic and delivers 1 moa. I have yet to personally witness anything better than 2 moa out of subsonic 223 and better than 1.5 moa out of 308 winchester.

Ranb

 

[husbandofaromanian]

Ha ha. Well, I kind of blew my budget on my .223 barrel. It's a 13" mgm barrel for my contender pistol. I guess I will have to to go supersonic if I can't get the subsonic accurate.

 

[greyling22]

I'd be happy with 2moa in a subsonic round. but I guess I just have low standards.