The only capgun I shoot (rarely) is my Mullin 8ga and for it, i use a round leather capper made as Piper suggests as I find I sometimes scratch the barrels with the Ted Cash capper. It's usually my son shooting the Mullin as I generally prefer the flints over the capguns anyway. To avoid double loading, I load concurrently. I hold the gun, butt on the ground and the barrels sideways between my legs and always start with the barrel furthest away. I put powder in each barrel, then OP wad but start both wads before ramming them home, then start both cushion wads before ramming them home, them shot in each barrel (furthest on first) then start both OS wads before pushing them home. Extremely unlikely to get a double this way as the only chance is a double powder or shot and in the slim chance that that were to happen, by ramming the wads down one right after the other, the difference in ramrod depth would be readily apparent.
