Mixing diferent Lots of the same Powder

[Calif Hunter]

I've done the same as Rocky for 30 years....

[BILLY D.]

Originally posted by Rocky Raab
The downside to that method is that it only takes one round to wreck a rifle.

I'd think it far better to distribute the few grains of old powder thoroughly amid the new stuff. You'd only end up with one or two kernels of the old stuff in each load of the new, and that cannot possibly affect anything at all.

Canister-grade powder must be within 3% of performance from lot to lot before it can be labelled and sold as the same powder. Most lots are MUCH closer together than that. That's why I've never had a problem with mixing the old into the new.

Or think of it this way: If the new lot is "slower" then mixing in a bit of the "faster" old lot will bring it closer to standard. The same occurs in reverse. If the new lot is "faster" then a dribble of the old "slower" lot ALSO brings it closer to standard. You cannot lose either way.

rocky

where did you come up with that little pearl of wisdom about the 3%?

sooner or later i'll repeat it and some body will say "where did that info come from" and i can't hardly say "well, rocky said it".

i have done some reading about powders and have never read that. i never knew the powders were formulated to such high standards and restrictions.

thanx bud

[Rocky Raab]

I can't tell you exactly, Billy. It's one of those things that I've read somewhere in my studies, but darned if I could quote a traceable source to you.

[royinidaho]

Just an example:

x grains of RL-22 in a 338 Win produced great accuracy and 2800 FPS MV. I considered this a bit more than maximum load. Case extraction was difficult but could be performed w/the palm of the hand whacking the bolt.

Ran out of RL-22. Went to a different store and bought a pound of a different lot. Never gave it much thought.

Same amount of powder and same everything else resulted in 2930 FPS again with good accuracy and out of this world pressures. Like a fool I shot a three shot group.

Its a good thing it was a strong action etc......

Thus w/any RL powder and new lot. Start low and rework up. Rocky's bench mark loads is a good idea.

[temmi]

I mix small amounts (less than 700gr) of “Identical” powder from different lots. While I do not load to the MAX published loads I have begun to crono “pet” loads. So I feel very comfortable shooting the first round through a crono and seeing where I am. That said… if I was closer to the MAX I would back off a bit… and work back up… I like to err toward the conservative side…

[Montana Cowboy]

Howdy All
I also have read the same 3% figure and can't remember where I read it. Been reloading for 30 years and have done the same thing mixing what was left in the old can with the new can of powder. There isn't enough powder in the old can to load one shell so mixing it wit a pound of the new powder isn't going to cause a problem.
Like a lot of folks here I buy 8 lb kegs so load development isn't a big issue with me.
If I remember correctly it was an artical about how powder is made and how the manfacture go's to great care to make sure that there is very little lot to lot variation from one lot of lets say IMR 4350 to the next lot of IMR 4350 powder. As was stated there is some difference and that is why they have the caution to reduce your load or start over at minimum load and work up when opening a new can of the same powder but different lot number. Was a back issue of the American Rifleman or Shooting times magazine where I read the 3% figure. MC