So for revolvers I understand you want to be right at or .001 over throat diameter to get a good seal and prevent gas cutting.
And in general for cast bullets you want to be .001 over the groove diameter to ensure a good seal.
I have a Henry 44mag/spl rifle. Henry stated the groove diameter was .430, and I just slugged it, and it came out to exactly .430.
My sizer is a .430. However the pressures I have been shooting are low, in the 13k to 14k PSI range. I am powder coating and then sizing. trying to achieve a sub sonic hunting load with 44spl's for my son. Hunting deer here in Indiana and a long shot is 100yds.
However I have been having troubles with bullets going into the target yawing at 25yds and sideways at 50yds.
my alloy is around 13bhn, recycled bullets that were sized wrong by the maker. (they replaced the batch for free )
I am wondering if my pressures were too low to cause the bullet to obturate into the grooves to seal properly.
my friends loads with the same bullets, sized the same, shoot great, but he is in the 17k to 20k pressure range. and I am wondering if the extra pressure is making them widen out and seal properly.
but back to my main question. I need to buy a new bullet sizer. do I go .431, or .432? or buy both and as the years progress and the bore wears I can go up to .432 later
and do you think going up .001 will solve my instability problems, or is there something else at work?