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270 WSM loads
Posted by Murphy on Feb 11 2005
pdavis,
The 270 WSM was a project of mine a while back and I have a little data on it. First I'm not familiar with the TSX bullet, is this a Barnes? Secondly, you say MagPro powder, do you mean RS Magnum or did I miss something else? I know there are a lot of new propellants out there but maybe I'm just getting old. Any way here is some of my loads for the Sierra 140 gr SBT: 72.0 gr of RS Magnum, CCI 250 primer, velocity 3112 fps. 66.0 gr of RL-22, CCI 250 primers, velocity 3120, 67.0 gr of IMR7828, CCI 250 primers, velocity 3189 fps. All with Winchester cases and from a 24" bbl. All are maximum loads!!! I don't understand the seating depth of 0.045". We normally measure that with cartridge overall length,(COAL) for the 270 WSM it is 2.860" That is the maximum length to fit the magazine also. If you mean the bullet is seated into the case .045", that wont work!! Also,
You can't really calculate velocity, you can estimate it or extrapolate it or you can measure it with a chronograph. The loading manuals will give the velocity obtained in there lab with each load, usually. Did you get your data from one of the manuals? Data is also tested in a specific barrel length, if your bbl is shorter,subtract about 1% of velocity for each inch of bbl. Does Kimber put 24" or 26" barrels on the 8400? I have several other loads if you are interested. As far as recoil goes,it shouldn't have any!! the beartoothbullets.com site has a recoil calculator.
This caliber is an attempt to carry on the popularity of the 270 Winchester and it is a slight ballistic improvement but would probably not be useful on any game the original couldn't handle. However, the WSM is a neat looking cartridge and fun to load for. I Hope this helps and good shootin'.
Murphy
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