I use .690's in my Navy Arms Double barrel and it shoots them real well. I get one large hole, 4 shot (2 from each barrel) groups at 25 yds. Mine has both barrels cylinder bore. I don't use a patch with mine, just the powder, an over powder wad, then start a half a lubed fiber cushion wad just below the muzzle and place the ball on it sprue up, then an overshot card, and ram the 2 wads and ball down on top of the over powder wad. In order to load the ball and other 2 wads easier, i punch a hole through the over powder wads before i use them. This gives the trapped air a way to get out and makes it easier to get the fiber wad, ball, and overshot wad seated without it coming back up off the powder.