Hello mates,sorry to disturb you! I have a sxs Chas Osborne 12 gauge shotgun and i send it over to gunsmith for repairing since i wasn't happy with the pattern of the shotgun.After 2 months the gunsmith kindly informed me that,the barrels were .37 thou and .44 thou.After, they have bored and regulated the barrels to 3/4 and Full(ie .30 thou and .40 thou). This is exactly what the gunsmith wrote me in their e-mail.

Can any of you gents explain me what does this mean in particular?

All the best!!

Kem