Ithaca Model 37 Featherlite 12 Ga. serial # 8552XX - My seach says mnfr'd. about 1963, is that correct? I also think the interchangeable barrels appeared around that serial number time? This gun is in need of a new barrel - I believe older models had to have barrels individually fitted, does this year / model fall into that category, or will it accept a new barrel (fully interchangeable) without fitting by a competent gunsmith? -- Barrel is bulged 5" back from muzzle - not my doing, recently aquired that way. Gun needs some TLC, but it's worth saving. Any input from you Ithaca guys out there? Thanks in advance.