I have been shooting a lee cast bullet, a 120ish gr trunketed cone style out of a glock 19 w/ lone wolf barrel. I may have just got lucky, but the results have been excellent. no leading, and this thing is a real tack driver. I prefer to run my bullets thru a lubesizer rather than tumble lube. IMO, tumble lube is a PIA.
Not sure what would be causing the bullets to not group and tumble. I would use the barrel as a gauge to see if they are chambering easily and headspacing properly. If not I would think there would be reliability issues if an auto, also.
