Jams I am assuming were failures to feed, which the longer OAL cured? That bullet loaded to fall between 1.260 to 1.265 OAL should run 100%.
Are you checking the sized cases with the gauge prior to loading? If so, and they pass, it is definitely a seating or crimping issue.
I cured sloppy seating (Not very straight), with a Redding Lyman M Die style expander and a Redding sleeved competition seater. It is also nice to be able to dial back to whatever bullet I am loading. Just the expander may have cured it by its self. Redding and RCBS have both copied the M Die style and all their expanders are made that way now. Good stuff.
Starting the bullets nice and straight? It makes a difference, even with sleeved seaters.
For crimp all you need is enough to remove the bell, or a hair more. I adjust the taper crimp die (And it needs to be a true taper crimp) so that the bell gets completely removed on the shortest cases, which means the longer ones will get a hair of inward movement, maybe .001.
Th epics in post #17 look fine.
Berrys 230 Gr @ 1.260/5 OAL.
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Purposely over crimped Berrys 200 Gr RN. Bad juju.
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