Pod this swaging method is the correct way to fit an external hammer to a gun and has been used for well over two hundred years irrespective of the country, as the saying goes if it aint broke dont fix it. Though there is only one other method I know of and was used by some makers on heavy recoil guns, this is both the gun lock mounting square and the hammer mounting square where both tapered giving a larger hammer to lock square mounting surface area and in doing so it acts like a full length taper fitting.
How to orientate the hammer? Well the easiest way is to make a template that fits to the lock square. This consists of a disc of metal roughly 1/8 inch thick about the average size of a hammer mounting boss with a square hole that will fit the mounting square (you can file this) to fit. Next you cut a rough hammer shape from another piece of metal but having a mounting hole that is round and will rotate around the mounting square. Then you fit both together by drilling two holes one above the other below mounting square, thread the round disk holes to take machine screws but the hammer shaped piece you make extended slots so it can be rotated. To use it you fit it on the locks square then rotate the hammer shaped piece to obtain the correct angle and distance from the firing pin, tighten the two screws to stop any further movement and this will give you the correct orientation of the mounting square to the hammer to the hammer boss.
I hope this makes sense in the end it is just an adjustable hammer. It does not have to look like a hammer as long as the face that strikes the firing pin is the correct angle.
