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Rifles, Reloading, Optics, Equipment
Reloading
How much does powder vary from lot to lot.
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<blockquote data-quote="goodgrouper" data-source="post: 203346" data-attributes="member: 2852"><p>Absolutely. Every powder and every maker puts lot numbers on powder for a reason. The reason is because they can't make two batches of any powder exactly the same. Vihta Vuori powders are probably the most consistent from lot to lot but as eddybo mentioned, they still aren't exactly the same. Alliant is the worst in my experience for lot to lot consistency. I have seen as much as 3% variation in these powder's burn rates and that is like the difference between RL19 and RL22. So if you worked up your load with a slow lot of RL22 and then buy another lot and it is on the fast side of 3%, now your working with a whole new animal. Re-testing is crucial.</p><p></p><p>Let's say you find a load with RL22 that has great standard deviation and produces tiny groups and it is 65.5 grains. You also notice that the velocities go up roughly 55 fps with every .5 increment charge around 65.5 and the load above and the load below give average accuracy and average deviations. Then you buy another lot of RL22 and it is slightly faster burning. Well, now it has bumped you up 100 fps at the 65.5 grain charge and the accuracy has gone away. So you have to reduce the charge to 64.5 grains or thereabouts to get the speed and harmonics(accuracy) back. This is very common.</p><p></p><p>Hope this helps.</p></blockquote><p></p>
[QUOTE="goodgrouper, post: 203346, member: 2852"] Absolutely. Every powder and every maker puts lot numbers on powder for a reason. The reason is because they can't make two batches of any powder exactly the same. Vihta Vuori powders are probably the most consistent from lot to lot but as eddybo mentioned, they still aren't exactly the same. Alliant is the worst in my experience for lot to lot consistency. I have seen as much as 3% variation in these powder's burn rates and that is like the difference between RL19 and RL22. So if you worked up your load with a slow lot of RL22 and then buy another lot and it is on the fast side of 3%, now your working with a whole new animal. Re-testing is crucial. Let's say you find a load with RL22 that has great standard deviation and produces tiny groups and it is 65.5 grains. You also notice that the velocities go up roughly 55 fps with every .5 increment charge around 65.5 and the load above and the load below give average accuracy and average deviations. Then you buy another lot of RL22 and it is slightly faster burning. Well, now it has bumped you up 100 fps at the 65.5 grain charge and the accuracy has gone away. So you have to reduce the charge to 64.5 grains or thereabouts to get the speed and harmonics(accuracy) back. This is very common. Hope this helps. [/QUOTE]
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