Tom,
It is a rolling block action made by Pedersoli with a Bobby Hoyt barrel chambered in 45-100 and stocked by me. It has a 1:20 twist and is 36" long. It is my current all around centerfire which I use for woodchucks, coons, strays, and target out to 400 yards, though most of my shooting (target and otherwise) is 200 yards and less.
I have had it in this configuration for about ten years. (Before then it was a 45-70.) I used to like Reloader 7 until it went overseas. I have found the new stuff to be corrosive (!) and not as good, so that is why I am working up a new load with 4198. It has always done well for me, but it meters poorly due to its grain size. So far I am happy with the results this time around, but I do get occasional flyers which are annoying.
I hope I am using the right term when I say "flyer." These are single shots outside the otherwise contained group. They are almost always within 3" of center at 150 yards--too far for good woodchuck accuracy--and seem to appear about one in eight or ten shots or so.
You mentioned seating depth, crimp and so on. So far, crimping seems to open my groups up, though I have only tried a profile crimp at this point. I have not yet experimented with different OAL, though for this bullet to engage the rifling, it would have to be pretty far out of the case to reach it. (It has a long ogive.)
KAF, thanks for the suggested reading. I had not heard of it. I looked it up, and it was printed in 1995, which was after I had been loading for awhile and after my spell of reading everything on the subject. I'll see if I can lay my hands on it somehow. (Oh yeah, and thanks for teaching me about Google.
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