Gentlemen:
I observed a Stevens 520-30 with a barrel serial number that does not match the receiver so it is clearly not original to the shotgun. The butt stock has a swivel so it was either originally a trench model configuration that lost its heat shield or the stock was indiscriminately used in a rebuild of a riot model. Although I have read some Forum postings about mismatched Stevens 520 barrels, I have not heard any discussion as to whether the U.S. arsenals used mismatched shotgun parts during rebuilds. In other words, I was wondering if there is any evidence that ordnance facilities overhauled shotguns after WWII in a manner similar to their rebuilding of M1s and M1911A1s. In those examples, we know that the manufacturer and era did not matter provided the parts were serviceable and fully interchangeable. Thoughts?