Bill: I learned about barrel sizes the hard--embarassing--way. I was at HC's in Terrell TX in '94, getting educated. I had a half-dozen Parkers apart, sorted by barrels, fore-ends, and the rest, comparing for nuances. When it came time to reassemble them I slipped a 20-bore barrel set onto a 12-bore frame, and couldn't get them apart. With my tail between my legs I told Herschel and he laughed; said "It happened all the time." I doubted it, but he took the mismatched barrels off the frame, much to my relief.
I guess most bbl sets are interchangeable except for exterior fit. This makes sense from a manufacturing standpoint. As to the 0000 frame from the 1980s, I recall it was break-thru news in the early to mid '90s when someone (Price & Mullins?) discovered (or rediscovered) the meaning of the numbers on the barrel lump and wrote about it. This makes me wonder if the 0000 Repro stamping was a private joke.
I don't know about my schedule. We were South in the Road Trek from the Vegas show in January till tax time...Illinois to Vegas to California to Florida (boat sold!) and north via John Davis in Ga to Eastern Shore, kids in Nokesville VA, and Illinois...9,800 miles @ 19.6 mpg. Somebody's gotta do it. We skipped Sanford because Middlebrook and Carmichael (who we visited in FL) said the venue prohibited overnight R/Vs (the usual "insurance" BS). C'est la vie! As to the Northeast...maybe, but I gotta know more. Investigation continues. EDM