Boats;
That Slip fit of the shaft would definitely be a concern to me. All the dial bore gages I ever used threaded together to a positive stop. Shaft markings would of course be a convenience but would not affect the actual reading of the gage. You would get the diameter of the bore, just wouldn't necessarily know exactly where you were measuring.
As to brands I mostly favored B&S with the exception of the dial calipers, Lufkin made some very fine tools in the past but went out of business about the time I entered the trade Starrett also made a lot of high quality tools, just didn't like that "Last Word" indicator, even though I have one of them. Finest micrometer I ever personally owned was a C E Johanson, Swedish made, of which I have two, a 0-1 & a 2-3.
Many years ago I bought a 20 gauge Flues. It was not pristine, had some minor pitting in the bores & had likely been hot blued. at some point. Barrels had been cut to 26", probably from 28" as there was some choke left. It was marked 2 &4 so would have been M/F when built. It weighed in at 6 lb even with the shortened barrels so would have been a bit more prior to cutting. This one was built in 1924. At that point I was unaware of the Frame Cracking problem & it was marked Smokeless Powder Proof so I fed it a regular diet of 2˝-1 loads, both factory & handloads using Unique powder.
Ribs eventually loosened on it so I retired it, didn't figure it was worth the price of having them re-laid. This was most likely from the past blue job.
