Pete, I am using a 68 grain Ammerman HPFB over 30.0 grains of N133 which pushes it to about 3380fps. It has not lost its tune yet (few 100 rounds).
I am now experimenting with an 80 grain Dominator HPBT (Bart's Custom Bullets). I am pushing it pretty fast over 31.0 N133 (barely compressed) which is about 3319 fps for its first outing. Case capacity for the Grinch is 30.9 N133. The 80 seems to be a bit more wind resistant. I had been using IMR 8208 but it does not seem to respond like I want it to.
I agree with Mike, use a drop tube to stack the powder into the case. I use a spiral funnel powder drop method into the case which works a lot like a drop tube. Next trip for the 80 will be at 30.8 & 30.9 just to see how well I like the result. I may start using a long (more than 12 inches) drop tube because it is faster and easier than my current method.
Have not lost the tune on the 68s. Have not settled on the 80s yet.
I agree, "It's complicated!"
I am now experimenting with an 80 grain Dominator HPBT (Bart's Custom Bullets). I am pushing it pretty fast over 31.0 N133 (barely compressed) which is about 3319 fps for its first outing. Case capacity for the Grinch is 30.9 N133. The 80 seems to be a bit more wind resistant. I had been using IMR 8208 but it does not seem to respond like I want it to.
I agree with Mike, use a drop tube to stack the powder into the case. I use a spiral funnel powder drop method into the case which works a lot like a drop tube. Next trip for the 80 will be at 30.8 & 30.9 just to see how well I like the result. I may start using a long (more than 12 inches) drop tube because it is faster and easier than my current method.
Have not lost the tune on the 68s. Have not settled on the 80s yet.
I agree, "It's complicated!"