Aside from the peg head, are the necks on the reissue Gibson banjos similar/same geometry from the nut to the pot? Will the cross-section of the neck as you wrap your hand around it to hold a chord be the same from banjo model to banjo model, ie RB3 vs RB250 vs Crowe RB75 vs ESS, Granada, etc. Did some banjos have thinner or fatter necks that made it harder or easier to play - straight out of the factory?
I've owned/played a number, and like most things Gibson, they vary. Not a huge amount, but some. The late RB 75 Crowe and Blackjack, and perhaps the "Vintage" Granada series made right at the end, had a cataloged "V" shape made into the neck. But for the most part, I think all the other models would be similar, with normal manufacturing variation over the years.
I've owned a GR RB 3 and Granada, played a late 90s RB 4 that I helped a widow sell, a circa 2000 Scruggs Bowtie, an early 2000s RB 18, an early 2000s Blackjack and an early 2000s RB 75 Mack Crowe prototype (both V necks). Played quite a few other Granadas and RB 3s. Never found one wildly different.
Necks were cut on a pattern machine, several at a time. Whatever neck was the pattern, the other necks were duplicates and then they were hand finished. Patterns could vary over time. I don't see much merit in trying to attach any significance to a particular model vs another. Luck of the draw.
For the most part the necks were all the same. I know 100% for sure that the necks were made using fixtures that utilized a spindle shaper and were machined two at a time. All necks were shipped to Nashville and were then shaped by hand by, I do believe by Ed Weber. Of course there would be minor variations but they were pretty consistent especially considering the volume. The Blackjack had a different hand shaped profile and the top tensions were a bit different since they had a thicker fingerboard. Hope this helps.
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