Re: 6mm Dasher Repeater for Varmints ? ?
I don't have any tube guns, but I do have two bolt action competition rifles in 6mBR and one in a 6 Dasher, all single shots. What action are you using? Have you talked to a gunsmith about the feeding issue? That would be my first step. Also - custom barrel? Tight neck?
Regarding the Dasher: You will need good sizer and seating dies. My Redding competition set cost $235.00 (only 2 dies). Then you need to learn how to create a false shoulder and fire form the brass. You will be able to get about another grain or so of powder in the case and maybe 150 fps more. For a varmint gun the standard 6mmBR will do fine for 500-1,000 yards. If you are re-barreling, look at the 22-250 Imp. or the 6XC.