Buffalo, try some 32 cal, cast lead round balls, pressed into the case mouth.
I was given a couple of hundred that were powder coated and gave them a try in a 308 Win, didn't work well and a 7.62x39 Howa 1500.
Those coated round balls shot very well from the Howa.
I wanted something bulkier than Bullseye and Unique and slower.
I used 20 grains of 5744 and it shot much better than I expected. Not good enough for head shots, but good enough for breast shots out past 35 yards.
The dead soft lead, used for the balls obturated very nicely into the grooves and left nice clean round holes in the birds/bunnies.
It was good enough that I even considered buying mould. Not for long though. Good sense got the better of me.
It dawned on me that the balls were just powder coated "0" Buck Shot.