I don't have a CVA, but do have a Navy Arms double barrel. Mine has both barrels cylinder bore. I use a .690 rd ball in it, and it shoots them quite well. 4 shots (2 from each barrel into one large hole at 25 yds. Still need try it at 50 and 75 yds to see how it does. I load 90 gr of Pyrodex RS, an overpowder wad, lubed fiber cushion wad, pattched rd. ball. For shot i normally use about the same load, except with 1 1/4 oz of shot. Don't know what the chokes are on yours, but if the ball will go down the barrel, it will come back out. If the 2 barrels are different chokes then you will want a ball that will go through the tighter one, or 2 different size balls, which would be hard to keep straight. :m2c: