I don't really know how to explain this, so here goes. I have a Marlin Model 30AW(I think Glenfield, but not sure) that looks to be in good condition. I don't hunt but like to plink and cast and reload for my levers.
The problem I'm having is with a cast boolit from an old(?) Lee GB mold for 31141 PB. I'm just now getting around to trying this mold and immediately ran into trouble. It is somewhat difficult to chamber a round. The boolet seated to slightly less than spec OAL, contacts the rifling which is MicroGroove. The impressed rifling is about .25 down from the flat end of the boolit. and the impression is .125"+long. Also the impressions are lighter on one side. I slugged the barrel and found a tight spot just in front of the chamber. Actually, it is tight at the muzzle and loose until the boolit gets to the area in front of the chamber. Measuring the groove diameter shows .305 which I assume is the tight spot I felt in front of the chamber.
Is this normal for Microgroove barrels?
If not, should I try a different boolit? Or, do I need to address the barrel some way?
I hope this is clearer than mud.