The chart below shows updated results for Blaser R8. Last week, I had tested loads with 68 grain to 73 grain of powder. Two loads at 71 and 72 grain gave great accuracy so this week I tested a load with 71.4 grain of powder. You can see the velocity for this load potted as '+' marks on the graph below. The average velocity is about 50 f/s below what I'd expected. For the new load, I had FL-sized the brass from previous test. Otherwise the components were identical.

My question: If we make round using new brass, fire it and then FL-size its brass, load again and fire in same rifle, should there be a noticeable change in velocity? My expection was that velocity should remain the same since the "internal chamber" of the case upon firing and once it is expanded to fit the rifle chamber is the same. So why did I notice a small 30 - 50 f/s change in velocity in both Sauer 90 and Blaser R8 rifles? And why in one case velocity increased (Sauer 90) and the other case (R8) decreased? cool


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Last edited by Omid; 11/11/17.