Is a variance in powder charge the problem?

[raider1v1]

I was verifying my Grendel load today before i loaded 300 of them. The load is 28.8gr varget w/ a 123gr A-Max, seated to 2.245 COAL and CCI large rifle primer. This is an AR-15 upper from Alexander Arms with a 24" Satern barrel. I do full length size using the Alexander Arms lee dies.

I was getting my normal group for a couple shots where they both touched, and then the third shot was about two inches low, but in the same vertical line. The rest of the shots grouped sometimes, but then others would be way off. either high or low.

I tried some factory wolf ammo and i was getting my normal .75"-ish groups at 100yds.

Everything about the brass, primer, seating depth was all the same. I am using a Hornady powder dump on my lock and load progressive press. I have read some people that have had issues w/ Varget in that that powder drop.

I'm thinking the issue is my powder charge variance after talking with some people locally about it.

Thoughts?

 

[ksthomas]

How much of a spread are you getting in your thrown charge weights? A little testing and some statistical analysis will go a long way towards understanding and isolating the problem here.

 

[raider1v1]

with Varget, I have gotten as much as .3-.4gr. I should have been smarter and saved some of the rounds i was shooting to measure the weights of the powder in them. Sadly, I was not thinking clearly at the time.

I am going to reload 10 and weigh each charge and then re-shoot them to see if that fixes the problem.

 

[ksthomas]

Think larger numbers here. That's a big problem with most reloaders; they don't evaluate a statistically significant number of samples to base a valid opinion upon. I would suggest that you check the accuracy of the measure itself to begin with, and see what your average charge weight variance is with thrown charges. Do 100 charges, and see what you're really getting. That's be a start.

For what it's worth, I doubt that charge weight variation of .3-.4 grains is the problem, so long as the load is within a proper sweet spot. Most factory loads (including the Wolf you're getting decent results with) will vary far more than this. It's about using a well balanced load, and one of the criteria is a degree of insensitivity to slight charge weight variations. Ten samples really isn't going to tell you much, but a very, very rough estimate at best.