All of the Belgian-made Ramshot rifle powders tend to burn very cleanly when pressures get up near max. First noticed it with TAC, in a .223 Remington 700 varmint rifle purchased in 2002, a couple years after TAC appeared. For some reason the factory barrel was one of those that never copper-fouled, right out of the box--but part of that, I suspect, was due to how cleanly TAC burned. The rifle would go 500 rounds without cleaning, and accuracy remained the same. I'd then clean it, just because, and accuracy would go to hell for 12-15 rounds before settling right down again--so eventually I quit cleaning it! Pretty handy on a prairie dog shoot.
I tend to be concerned with velocity variations in cold temperatures, due to mostly hunting big game in Montana, and have tested a bunch of loads with various powders at both 70 and 0 Fahrenheit. Big Game has lost an average of between 19 and 36 fps in several cartridges, which is right in there with the Hodgdon Extremes. Among the loads tested was Big Game with 150-grain bullets in the .30-06, and a little oddly the velocity loss was LESS with CCI 200 primers than Federal 215s. Like Charlie, I have often found Big Game to burn more consistently with magnum primers--but not always....
