Nice job!!
I've worked in a foundry for 39 years, we used to make all sorts of stuff when the gaffer wasn't around, can't do it now though as there's cameras everywhere
My bro in law's lad had a 1377 crosman some years ago and the plastic enplug snapped so I used it to make a mould then poured one in aluminium, it turned out fine and he could carry on with his plinking!!
John