Re: Rem 300 Ultra Mag using Sierra 200gr HPBT
Iron worker, good point. I tend to put bullets pretty far into the lands, and typically use long Lilja 3 groove barrels, all of which may vary quite a bit from your set up. If you have loaded H-1000 in your rifle, just note that Retumbo will be about 2 grains slower than H-1000 with the same bullet, all other conditions staying the same. Start in a safe place, and work up.
I have to agree with Texas Dave in part.... I have not had great results with bullets lighter than 180 and Retumbo, but Retumbo shines with bullets 200 grains and heavier.
The Nesikas tend to shoot comfortably with a little higher pressure than say my win mod 70, so you have to be careful about trading exact loads. Listen to your rifle's pressure signs and load accordingly.