As you surmise, the .577/.450, Martini-Henry CAN easily be loaded IF you are doing it legally. Remember that you will be asked to justify the acquisition of suitable large rifle primers to set the things off, as well as a BP license to obtain the bangy stuff.

However, please note that there WERE official smooth-bore versions of this gun made available at the time of issue - the lack of rifling being more for the purpsoe of ensuring a miss rather than a hit if the gun was 'inadvertantly' aimed in the wrong direction - á la Indian Mutiny and the subsequent Sepoy-issue smoothbore Pattern 53s. Obviously such a gun would be off-ticket, until you expressed a wish to shoot it.

A shooting pal on this forum and in our club legally shoots his large and varied collection of M-H rifles and carbines- I hope he turns up soon - the M-H is not in my area of extened knowledge - his most certainly is.

tac