- Joined
- Feb 21, 2008
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Here's a wierd one. took my Chrono to the range to see what weighed T7 charges( 2f)were giving me in my Black Diamond XR .50 cal. The load was CCI musket caps on a single vent Ampco nipple a 250 gr .45 Hornady XTP in Harvester crush rib sabots.The weighed charges were 45 and 50 grains. The first up was the 45 gr load. Group size was 2 5/16 for 3 at 100 velocities were shot 1521, 1528 ,1562 fps. Group2 ,50 gr 2 3/16" velocities 1669 ,1617 ,1533 fps Group3 3 15/16" velocities 1523,1583,1517 fpsThese are the 50 grain charges! Group 4 45 gr 2" group , 1548,1490,1521 fps.Interesting that by the 5th shot velocity takes a dive.The barrel is swabbed between each shot thoroughy too. I'm going to try a flamethrower nipple to see if the effect is repeated. Point of impact is not effected by the change. The shot to shot variation is also larger than I like. Group 1 41 fps ,2 63 fps 3 136 fps and 4 66 fps. I am careful not to have the patch saturated to the point where it dampens the breech and effects the powder.I also thoroughly dry the bore as well.These loads are alittle larger , and in the case of 3 , significantly larger than this rifle usually gives. I'm confused as to why this is happening. Anyone else out there see this effect? I got into the habit , when I chrono loads , of shooting every round I brought with me. Glad I did! Any ideas?