Hi, I wonder could I ask some advice.
I have worked up a few good accuracy loads for my .20 tac using ramshot xterminator. However, when I came to chrono today it looks like I'm not even coming close to the velocities quoted in the load date.
Load is as follows:
cases: reformed .223 lapua match
primers: cci 450
powder: 24.2gns ramshot xterminator
bullet: 40gn v mamax seated to book col
barrel is 24 inc Pac nor
now the manual reckons for this bullet powder weight combo I should be around 3600 fps but my chrono reads 3450 which the book reckons I should be seeing from just 22.2 grains! No pressure signs to speak of, just the tiniest bit of cratering on the primers but this load is still well short of max!
Anyone suggest a possible cause? I'm not using the same primers but surely it couldn't make that much difference?
thanks for any advice!