Normal for volume of powder to change with different lots?

[Adam Gibbs]

I've been loading for a 30-06 for a little bit. Worked my way through 1 partial pound of reloader 15, then a full one. Charge weight is 55.0gr. My thrower throws right at 54.9 or 55.0 pretty consistently.

I opened up the second new pound of powder and now it throws at 54.4 or 5 every time. Is that normal to get that much weight variation with different powder lots? It definitely filled up more of the case to where I can't hear powder moving at all when I shake a loaded cartridge. When working the load up, I hit pressure at 55.5gr, so I backed it down to 55.0 and called it a day. I'm guessing I'll be running into pressure issues now if my case is filled more?

 

[RockAndSage]

That's interesting, I'd like to know if that much of a difference is normal too.

The only thing I can offer is that when powder's manufactured it's not one "lot" that's made all at once in one big machine, but a large number of much smaller batches. Each batch will have its own variances, and the way they make a lot uniform is to just mix all the batches together.

 

[Firth]

Normalish probably. I haven't done enough testing to know how common it is, but I've seen similar stuff enough that I don't think it's uncommon. Little changes in humidity during manufacturing can cause what you're observing. The manufacturers control what they can, but nothings perfect. I always do a little testing when I start on a new jug to see how different it was from the old.

 

[seand]

Only way to know is to chrono. Lots vary, and so does powder water content due to humidity. 1# cans are a PITA. Save an 8# jug and then when you have to run 1#’s (avoid if you can) dump them in the big jug and mix them up so they are the same.

 

[SloppyJ]

Sounds like the size of the kernel changed and now they're not as dense? That seems odd to me. I could see a tenth or so but what you're describing is excessive IMO.

I trickle all of my precision stuff but I haven't notice anything like that before.

 

[DaveCB]

From one batch of components to another it is recommended to reduce your load by 10% and work up. stated in all good reloading manuals.
Why! some times it can change a little other times a lot.
from pound to pound for powder, From one batch of primers to different brands.
Case volume changes with each time you fire a batch of cases due to spring back.
not by much but it changes.
I buy powder by the largest lot I can, primers by the 10k lot.
for the basic reloader that my not be normal.
I use to blend my powders and call that one lot. the powders are better made and consistent.
Hope this helps.

 

[wind gypsy]

Like others have said, it's hard to say what the performance difference may be. Could just be longer sticks of powder that don't compact as well and in that case I'd expect lower velocity/pressure. I've never used a powder thrower so have no related observations but i don't recall case fill rate ever varying that much lot to lot.

Could be slower, could be faster, only way to know is to shoot it.