I was breaking in my new 7mm wsm barrel today and gathering some velocity/pressure info at the same time. I got some way lower velocity readings than I expected and suspect I may have miss set my scale. I want to know if the predicted velocity would jive with my suspected error. Rifle is 7mm wsm with 3 groove 9 twist barrel at 25.25". Powder was Retumbo pushing 168gr berger classics lit by wlrm primers in WW brass. I got readings of 69gr 2757 , 69.5gr 2808 , 69.7gr 2860 , and 69.9gr 2840. The powder burned very poorly. You would have thought I was shooting black powder the barrel was so sooty after each shot. Either the powder is going bad or I may have miss set the beam scale I was using 5 grains low. What I want to know is what the predicted velocity would be for 64gr , 64.5gr , 64.7gr and 64.9 gr. Either way I threw out the last quarter pound of the Retumbo I had that had been open for a year in un climate controlled storage. I would still like to know if I screwed the pooch but got lucky or if the powder was bad.
Oh , the velocity readings come from my brand new Magnetospeed I got from here. It was right were I thought it would be with my 7-08 loads so I have confidence that it was not the problem.
And the temperature was 97.3ºF 58% humidity and basically sea level.
Oh , the velocity readings come from my brand new Magnetospeed I got from here. It was right were I thought it would be with my 7-08 loads so I have confidence that it was not the problem.
And the temperature was 97.3ºF 58% humidity and basically sea level.
