Just curious?

What kind of lot-to-lot variations in GRAINS have you experienced from a particular powder?

2-3 grains or more?

How many grains difference from lot to lot of powder is going to depend on the cartridge and bullet weight used.

Many years back when researching US M1, M72 and M118 ammuntion I ran into a specification for M72/M118 ammunition with IMR 4895 that lot to lot variation could not excede +/- 5%. That seems to be the case as I've pulled and weighed powder charges of 4895 from a whole lot of M118 different lots. They varied from 40.5 up to 42.5 gr. That is a 2 gr variation. 2 gr is right about 5% of that charge. So it appears that IMR was pretty consistent. A couple industry insiders (they, for the most part, will not reveal trade information like that) have told me that percentage was pretty large close to standard but that the actual lot to lot variation was much less.

Unless we see something from the powder manufacturers (which is unlikely) it is hard to say for sure. If you are pushing a max load then it is best to drop back 10% and work up again if a new/different lot is used. Better yet is to buy in large quanities like 8 lbs jugs. Then a max load worked up for that lot of powder can be used for a while without having to work back up.

Larry Gibson

Thanks Larry...I'll go with the 8# jug