View Full Version : Powder lot variability

02-22-2008, 08:04 AM
After quite a bit of experimentation, I found an exceptionally accurate, mild load using an older lot of Varget. I recently used up the last of the old lot and purchased an 8 pound jug of a newer lot. Using the load developed with the old lot, my groups with the new lot have grown about 50%. Powder lot # is the only variable that has changed.

Is this normal? When I work up a new load, will it shoot as well as the old load?

Thanks for your help,

02-22-2008, 08:52 AM
I have experience this exact problem with many powders, but it was most pronounced with Varget. That is exactly why I only by 8 lbs kegs of the powders that I shoot and try to make them work before experimenting with new ones.


02-22-2008, 09:08 AM
There can be a great deal of difference in powder lots. Sometimes this has to do with the business plan of the vendor. They may even be getting their powder from different manufacturers. That is why, for years, factories wouldn't tell anybody what load they were using. They were using the cheapest powder they could find on the market which would give median performance. A tip: If you want to know about what an average factory round's velocity is, look in the loading table in a manual go to the left until you find a velocity in which every powder listed offers a load. That is about what factory ammo will do. Of course, +P and premium ammo excepted. There are other variables with powder. Excessive handling and vibration will cause powder to burn at a higher rate. Basically, powder is all the same stuff. Size and shape of the particles, and density of the mix are the only real variables. The other day somebody mixed Varget with 4350. The advice was to throw it out. No doubt a risk free option, always good to err on the side of safety. But if you blend it lightly, you have a powder which will work for median loads in medium cases with medium bullets. Work up a safe load. Chances are this blend will rate within tolerances same as the next lot of either powder, depending on the ratio.

02-22-2008, 10:11 AM

Blending powder? Not a good thing for guys who don't know the dangers!!!

02-22-2008, 11:00 AM
Long range and Palma shooters have complained for years about the variable burn rates associated with different lots of Varget. The solution that most of us use is to buy as much as you can, maybe 3 or 4 jugs, work up the load, and you're set for a pretty long time. When you near the end of that lot of powder then you start all over again. You usually don't have to vary more than 1 grain on a load of 46 to 46.5 grains.

02-25-2008, 07:52 AM
I don't advocate blending powder "for people who do not know". I said err on the safe side, stick to the cookbook. But, people who "do know" blend powders on purpose, also, people make up duplex loads, even triplex loads. people do this for many reasons. Top performance from a specific arm, use up a whole bunch of powder which won't give the desired results by itself, etc. If you are loading for a .243 with an 18 inch barrel you may use a different powder than for a 26 inch barrel. People reload for all kinds of reasons. I have a friend who has reloaded for 40 years. He loads for a 30-06and uses a lee loader. He uses the same load all the time. He loads to reduce recoil and save money. Advance loaders understand the relationship between case capacity, bore diameter, barrel length, burnrate, bullet weight, bullet coating and bearing length, and how all this effects the time pressure curve. Called interior ballistics, it is a known science and has been at the state of the art since Paul Mauser's time. details change, but the math is the same. The guy who road down to the gun show with me on Sat. has been around alot onger than I have. He said that once they had vast quantities of 50 BMG powder and were using it in large straight walled cases. Totally unsuited powder. But, they wanted to shoot. So they kick started it with bullseye and got an acceptable level of performance.