The gun has been re-jointed badly. There should be no light visible through the barrel breach end and the standing breach. It may not wobble because it has been re-gripped and is being held tight by the bolts.
Poor re-jointing can leave a gap between the barrel flats and bar flats (what you Yanks call a 'water table'). Also look at the radius, there can often be a gap left there as well.
Then check the doll's head fit. amateur gunsmiths struggle to get it right on all the surfaces that need fixing straight when multiple bites are involved.
Also worth checking to see what the headspace is like in the rims, sometimes you will find the barrels have been filed uneven and the rims are deeper on one side than he other and the barrels effectively slanting to one side.
