No expert here but that crown could use a polish.. looks kinda unfinished/ rough..
You could make a crown lapping tool and some grit paste and hand lap it pretty and maybe run some girt paste/ polish through the barrle some especially at that last inch of choke at the muzzle end...
No guarantee but some thing to try out ..
For these hatsans leades that has a sharp edge around the hole i used a #2 pencil eraser i shaped to bevel out that sharpness. Then spun it between the palms of my hands and cut w nice smooth bevel .
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