TBH, here in UK there's not a lot you can actually shoot with a Cape gun of any kind. Problem is, y'see, that here in UK, although it's a muzzleloading antique, or a b*e*c*-loader that shoot obsolete c*t*i*g*s and Mr Courtney could buy it without an kind of of permit or authorisation, actually SHOOTING it is a chicken of a different blanket.
If you want to shoot the thing, well, it's that rifled barrel, y'see - makes it, here in UK, a Section 1 firearm. Same a .50cal Barrett [excuse me].
So it's really not a matter of how many rounds you fire, it's actually being ALLOWED to fire ANY rounds. And at what? Minimum m/e for deer is 1750 ft lbs. It MIGHT make it, but getting it authorised to use? Hmmmmmmmmmmmmmm.