Y You won't get 400 yard accuracy out of a double rifle. A good double is tuned in such a way that shots from both barrels will cross one another at a certain range. That particular range may vary from rifle to rifle but I believe is usually about 50 yards or a little more. These rifles are designed as relatively short range stoppers of charging game. The technical problems with having both shots precisely parallel each other, an inch or so apart, out to 400 yards are huge. Kodiak percussion black powder double rifles have attempted to 'solve' the problem by having separate front and rear sights on the right and left barrels. Then both barrels must be sighted individually in which case it is possible to get some accuracy for either barrel out some distance. It means having to move your eye to sight each barrel separately, hardly a good solution for a desperate situation.