I got out yesterday to try a couple different combinations.  Just out of curiosity I loaded five each of two different lengths.  One group using the upper crimp groove, one the lower.  OAL with the rounds crimped in the top groove is 2.985" and the OAL with the crimp in the lower groove is 3.085".  Feeds them just as slick with either length. There was no difference in overall group size, but it appeared the deeper seated rounds were more consistent, the shots between the extremes were closer together.  Perhaps with this hard copper being what is taking the lands, a bit of a run at the rifling is a better thing?  With a case trimmed to the proper length, the bullet is just barely in the case mouth when the ogive hits the throat.  With the bullet crimped in the upper groove, that makes for a full 1/4" jump, but it appears to like it that way!  I have some SPP210 powder that Wideners sold cheap a long time ago.  After a bunch of digging around I found it is likely Vectan TU2000.  That, in turn, burns approx 4198 speed.  Max load of 33gr.  With a 30" barrel, velocity should still be up around 2700fps.  Very clean burning powder with not much gas pressure left to blow out the muzzle, sorta snappy.  Center round was seated using the rifle, with the bullet in the throat.  Measured center to center on the black lines, squares are only .930".

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