Eric:

No bridging with #4. Loaded up some #1 bismuth and had bridging on a few, but nothing a little whack upside the MEC could not solve.

Not sure what you mean re “shot rub through.” Have not inspected any wads after shooting, if that’s where such a thing would be observed.

-Victor

I doubt that you will get any rub through with Bismuth , it is pretty soft , compatible to lead . It wouldn't hurt anything if it did .

Thank's Victor and Mark. I was concerned with shot bridging in the barrel using large shot without a buffer and the chance of large shot rubbing through the standard lead shot cup. I am interested in low pressure 1200 fps 12 and 10 gauge bismuth hunting loads.

I had posted earlier that I was using 23grs of GD for clay birds. Actually I'm using 21.5grs of GD and 1 ounce of shot with the SP-10 wad, 16ga filler wads, and Cheddite primers. Don't remember how dirty the barrels get, but they smoke the clay birds very well. When it warms up a bit, I'll get the 10's out again and check the barrels when I'm done. In the 12ga, GD is used with 7/8oz loads, so hopefully 1oz loads in the 10 should be fine.