Home Forums Reloading Big Game Rifles Critique this shot session,

15 shots, spread of 93,

Seems like a lot, That normal or no?

What factors cause this and can it be tightened up?

The particulars if curious,

5.56 rifle. 25.8 grains of CFE223 16 inch barrel

Bullet weight?
Primer?

Be interesting to see the comments. For me, I'd start with powder charge. That is assuming everything is already as good as you can make it, or very reasonably good with your brass prep. Neck tension that's not way out of line from 1 cartridge to the next, trimmed to the same length, flash holes deburred, (some case brands are bad, some aren't) cases annealed, etc.

Assuming that all is a given within reason that you're starting out with quality prepped brass, then for me it's powder charge to get your components working together and get that consistent velocity.

69g Sierra HPBT. CCi 400 primers

Once fired LC brass, that was tumbled, swagged, trimmed and chamfered.

CFE 223 is after all is said and done...like all ball powders, a double base powder...you will get higher spreads...you can juggle primers...you can pay more attention to uniform neck tension...if it was cold, you can try again at a more temperate ambient temp.
Yes, I know CFE was designed for the 223, but nitro is nitro, and it is not as stable as single base, if you do not know the storage history or age, who knows?
After investigating, you can't figure it out...try some 4895 at the same velocity, I'd bet your spread will drop to the 20's.

Cause #1 you have more than 3 shots. The trick is to cherry pick so you can say ES 10 and SD 1.

Is it normal? Absolutely, if you fire enough shots to get a true ES SD you are going to see that. Try throwing out the high and low as flukes and see what you get.

Several guys around here have had better luck with mag primers and cfe223

Here’s another string, Same day, Same rifle, 12 shot string (I know, that’s not much of a base line, but the same pattern seems to be establishing its-self)

This powder is 25g of Varget, all other components are the same, again almost 100fps diff………

Temps were about 30F

4895? I’ll keep that in mind. 8208XBR is the next victim.

Curious on what relationship here is causing occasional flyers,

Next time I’ll keep track of flyers and that particular shot,

Buying a good chrono is like buying a good borescope, Why would you do that? Opens a lot of doors,

Like my ADHD can cope with this………

Grin.

8208XBR test should tell you a lot...Australia's answer to avoiding double base powders, is 8208, a single base...but don't ignore the hint on neck tension. If you have ever pulled many NATO spec cartridges, you know, between lacquer and neck tension, it's a tussle. Not saying you need X amount of neck tension...saying you need uniformity.

Other than annealing, how can we try to control neck tension?

Expander ball diameter? Collet die and collet die mandrel custom sizing? And then, I hate to say it, gasp, Lee Factory Crimp Die? I will be hounded off the 'Fire with that suggestion...been nice spitballing ideas with you though.

Using brass brands with thin necks could help along with sorting for neck thickness. I'd rather anneal.

8208 is definitely worth a test. I get great accuracy with low SDs in my .308 Palma rig with 155s which typically uses powders of a similar burn rate to your .223's requirements

Have you tested your chronograph for accuracy?

This, plus annealing and neck turning.

Not really, Could add that to the list I guess.

Standard velocity .22lr, especially match grade, is a good test for Chrono accuracy. I think I read that in one of Mule Deer's posts and it works for me.