Helping my bud re-insert the barrel on his Polish PMKMS kit using a xebec jig.
The rear sight tower is canted slightly, so we stopped.
Tried to crank her around using some channel locks and vice grips. Its not budging.
Can't press the barrel back out because the receiver is now on.
Well the way I would and have resolved this is as follows:
Take a big brass punch...
Kinda like this one: harbor punch
Not sure if that's the same one I have or not, when I got mine it was a single punch referred to as a large brass punch, but it appears to be the same.
Then comparing the punch to a front trunnion I ground a band down on it so it fit better between the rail guides on the trunnion but was still about as large as the breech face.
To get it back out, set the front edge of the receiver on the edge of your workbech, lock the punch in place against the breech, yes it will be at a slight angle because the receiver is on there, but with the soft brass punch it doesn't matter. the punch material will give way...
Tap it with a 2lb. hammer and the barrel will pop right back out.
Lacking the brass punch you should be able to achieve the same results with some pennies and any other rod. I've used a stack of five pennies held together with a band of electrical tape and a steel rod for stuff like this. YMMV.
But you can get the barrel back out with the receiver installed.
Also you might try some kroil on the barrel where it's already isntalled in the trunnion. Then a nonmarring hammer blow or three to the sight block might get it to twist. However that process risks damage to the parts more than just knocking the barrel loose again and realigning.