Crazy lot-to-lot consistency with Staball Match?

[FrontRange]

So, I’ve been using Staball Match for a couple of different cartridges (6.5 Grendel, 6ARC, AND 223) and have been generally quite pleased with velocity, temp stability, accuracy, and sds. I bought another pound and loaded some 6.5 Grendel with an established 31.0gr load at 2420fps (inline with Hornady and Sierra data) without worrying too much about lot differences and needing to work up because of the relatively low pressure in a gas gun. However, I didn’t expect a 120fps DROP in velocity. I went home and checked my charge weights (they were the last charges I dropped) and, right on the money, 31.0. This is basically a full case up into the neck so I don’t think I can get much more powder into it. I haven’t tried this lot in any other cartridges but, at worst, I can use it for 223 practice. I’ve never had anything like this happen at least not anything that changed velocity by more than 50fps. Thoughts? Does this happen? Thanks, I’m a little at a loss?

 

[A382DWDZQ]

Someone left a tip on here a while back to always set aside a handful of the old powder loads for benchmarking when you move lots. Do you have any of the old loads, and/or did you already check against them? Fire one new and one old in the same session? Lot variance happens, that is my understanding of why QuickLoad has the 10% +/- lines. Good luck solving this!

 

[FrontRange]

Someone left a tip on here a while back to always set aside a handful of the old powder loads for benchmarking when you move lots. Do you have any of the old loads, and/or did you already check against them? Fire one new and one old in the same session? Lot variance happens, that is my understanding of why QuickLoad has the 10% +/- lines. Good luck solving this!

Thanks and that’s smart but I ran the last can out. Loads were from the same set of prepped brass, same primers, same projectiles, measured on the same scale that is regularly checked during loading (my sds are still good enough), shot 2 weeks from each other and I’ve shot several from the previous loads outside more recently with expected changes due to temps. Only thing switched was the powder. Both strings were shot at an indoor 100 yard range so I don’t think it’s environmental. I’ll try to fit more powder into a case but it’s already pretty compressed. I’m used to some variance but I’ve never seen that big of a drop/increase, although I guess it falls within a 10% variance.

 

[HairyScandinavian]

Any updates or changes? I just had 2 lbs delivered I was planning to play with for the 6 ARC and poking around the forums for info and came across this thread. I guess it's good that it dropped and didn't go up and cause an overpressure condition, but it doesn't give me confidence being brand new to all this.

 

[FrontRange]

Any updates or changes? I just had 2 lbs delivered I was planning to play with for the 6 ARC and poking around the forums for info and came across this thread. I guess it's good that it dropped and didn't go up and cause an overpressure condition, but it doesn't give me confidence being brand new to all this.

Yeah, short story is I loaded more from the same lot in both ARC and Grendel and confirmed it was MUCH slower than the first can I had. I’d had very good luck with Staball Match as far as accuracy and velocity from the first can with speeds generally a little slower than published data—but reasonably close. It was typically about 25-50 fps faster than the corresponding max loads of Varget with similar accuracy and slightly higher sd’s, which are fine for my purposes. Using the second (slower) can, I still had good enough accuracy but nowhere near the speed I had been getting. I quit trying to use it in the ARC but made some progressively heavier loads for the Grendel. Hornady’s max load for the 123eld is 30.7 with an expected velocity of 2450fps in a 16 inch barrel—and I went up to 32.3, which required a percussion massager on my reloading bench to get the powder below the neck. At 32.3gr, velocity was 2400fps, still 20ish fps slower than I had been getting from previous 31.0gr loads and much slower than published data. I loaded up 10 at 32.3, vibrated them all down, and they shot fine (about 1.3 moa) but the juice really wasn’t worth the squeeze (I was also dicking around with Benchmark and have since discovered this rifle loves it with just a little less velocity than Varget). Based on ejection patterns, these were also running at a lower pressure. I also grabbed another can of Staball Match at the range and came home to find it was the same lot number as the slower can, which was purchased elsewhere. Loaded up a few with the (now) third can and they shot exactly the same as the as the second can. So, sorry for the long story, but it seems like recent lots have been significantly slower than my previous can and are nowhere near published load velocities. I would work up slowly toward published velocities and expect compressed loads. I use Rexus Ultrabolts and am not scared of reasonably pushing max AR loads but I don’t think your going to be able to get enough powder in a case to be able to do any damage to an ARC if you’re using some of the slower lot. I’m still using it for 223 blasting ammo and it works fine in loads somewhere between 223 and 556 levels. I’ve attached a pic of the lot number for the slower cans.

 

[HairyScandinavian]

Wow, thank you for the well written detailed update! I ran to look at my lot number, luckily it's 1110525+2015 so maybe I have a good batch but either way it's only 2 lbs so I need to be aware of that for long term considerations.