Years ago I worked up a 22-250 load with H-380 & found that 36.5 grains was the max in my rifle & gave about 3700 fps when the book said 39 grains. Got a bottle of powder from a different lot and discovered 36.5 grains was only giving me 3350 fps. I could load 39 grains with the new lot. Scary stuff. Powder makers say it is extremely difficult to maintain consistency from lot to lot & that they make sure it is "below" the burning rate tolerance for that powder to avoid safety issues. YEAH! And I didn't have sexual relations with that woman either!!! When I find a load that works good I try to buy a keg or 2 of the powder with the same lot #'s.
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