Popper, I've played withe BLL and PB soft bullets in my Marlin too, and had issues. If I get the bullet seated right up into the throat, and use a little Dacron wad, they work fine with BLL. If I don't use the Dacron, they pattern rather than group. If they're not contacting the throat when chambered, I get big lumpy lead fouling for the first 3/4" of the bore. If I PC them, they shoot ok, but not great due to wild SD with the light powder charges. If I use regular lube in the grooves, no BLL, seat them to engage the throat when chambered, they shoot under an inch at 50 yards without any leading or further detailed load tweaking, and there's lots left to tweak. Now that I have my 50-yard berm finished I'm going to do a little experiment to compare seating depth and BLL vs standard lube. The plan is to shoot three groups of ten, with the known good load in the middle and the deeper-seated load that leads the throat last, and recover the bullets from each batch in crumb rubber to see if the gas cutting and base band damage relates to the group sizes.