No4 receiver out of square

Hi guys, I bought a fair condition No4 the other day, with a knackered barrel. The body had lost all its sharpness and all manufacturing marks were gone (hit hard with a wire wheel is my thought) , It had clearly been phosphated and painted after this. The "England" stamp had been done after the painting, so it must have been done a while ago, 'back in England I suppose.
Rego papers call it a "parker hale" as the manufacturer, my guess is standard British manufacturer No4Mk1
Anyway I removed the old barrel, and was going to put in a second hand but less wornout one, and when I screwed it in by hand I could see as clear as day that the shoulder (on the barrel) met with the breech face at 6 o'clock, leaving a 1/2mm gap or so at the top (12 o'clock). Same with another barrel, both barrels mate up okay on other bodies.
Is this common?

Never seen this TBone but I would suspect that the old barrel has been fitted by a butcher who has filed the breeching-up face of the body. BUT hasn't filed it square.

How do you correct it......... I'm blowed if I know. Obviously we'd just scrap it after asking who started the job then taking the xxxx out of the offender! You could screw it onto and lock it onto a stub of the chamber end of a scrap barrel, clamp the barrel in the lathe chuck and face the body breeching up face off. THEN use an L1A1 breeching up washer to return it back to length as you're re-barrelling it

On second thoughts................

It's all in front of you Tbone, put the old barrel back in, grab your trusty letter stamps and go crazy with DP, theres a Father/Son combination out there that will be only too glad to take it off your hands for future refurbishment and onselling.