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Old 01-25-2013, 10:55 AM
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FMJBT FMJBT is offline
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Location: Los Alamos, NM
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Got some interesting results from the last trip out to the desert. Taking notes on bullet drop for various loads at 650 yards, I've reverse engineered the drop using the android app "Shooter" to come up with a velocity for the loads.

My standard load is 23.8 grains of Ramshot TAC in LC brass using a Nosler 77 grain CC seated to 2.25" COAL. Primers are CCI #41. At 650 yards, my drop for this round is 5.5 mils at an elevation of 1500 FT. This gives a velocity of around 2710 FPS according to the "Shooter" app.

I loaded up another batch of basically the same round, only using 24 grains of Hodgedon CFE-223 in place of the 23.8 grains of TAC. These rounds were only dropping 5 mils at 650 yards, with a muzzle velocity of around 2820 FPS if the app is correct. Pretty impressive numbers out of an 18" barrel.

For both of these loads, I worked up until I began to see flattened primers, then backed off 1/10 grain for the final load, so these are both right at the the threshold for showing pressure signs out of my SPR. I definitely wasn't expecting to see such significantly higher numbers out of the CFE load. I think the next test will be to try the CFE powder with the slightly lighter 75 grain Hornady HPBT's to see how fast they can be pushed out of an 18" barrel. The Hornady bullets have a better BC than the Nosler (.390 vs .340), so it should add quite a bit to the usable range of the rifle.
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