A person could go over my last post and might not get what I'm trying to say. I could make it a lot more understandable if I simply say…….
I think any gun smith worth the salt would do what actually solves that arbor fit problem. Use a lath and turn out a new arbor that is a close tolerance fit in the barrels hole. Make sure the barrels hole is reamed a little for straightness and smoothness. Make sure the arbor is the right length to be bottomed out.
I think the arbor should be about .002" under the diameter of the barrels hole.
I'm getting at saying the arbor length isn't the only thing that needs to fit well. The arbor has to fit the barrels hole well too. You know....like those two things should merge as they are one.
Making a new arbor and fitting it is a bit of a chore but a good smith with a good lathe can do it straight forward. A good machine shop with one of those wire type cutters(don't know the real name) can make a slot in the arbor perfectly. I had a shop do it for me.
I don't have a lathe,only a miling machine, so I had to look fer some help from a machine shop. The new arbor fer my Navy is a real gem. If I had a lathe I could start a hobby business being an arbor maker for people wanting the best fit fer the open top Colts.
Hope someone reads this since I think itsheds some light on the subject of scientific propblem solving. You know.....just getting an arbor correctly bottomed is not doing the whole complete job. You need the arbor to fit the barrels hole well diameter wise too.