Re: vz 52 rifle?
On the chambering, note that the bolt face is countersunk so that it will work with a cartridge that sticks out of the chamber 1/8 inch or so. That is why a 7.62x39 won't extract - it drops in with the head flush with the end of the barrel and there is no way the extractor can grip it. But the longer round should not protrude any more than the depth of the countersink. Is it possible there is something in the chamber preventing full seating of the 45mm round?