Jerry
At risk of thread drift, what do you think of this?
Barrel switching between a 1977ish "A" series and a 1959ish pre "A".

Dealing with 2 barrels each age (4 barrels total) that work fine on their respective pistol frame. Early barrel gun combination works fine. Later gun combination work fine. But put early barrels on later frame or vise versa, both wont feed. Barrels all seem to fit either frame just fine. No hangups in mounting at all. Magazines all work in either feeding gun, early or late. But they wont feed if they are in a mismatched age of barrel and frame.

77ish barrels=original 5.5" (relined by Alex Hamilton, D&T by Roddy Toyota) and more recent 7" (Millet sighted) cut to 5.5" from Gil Hebard. (The cut barrel has grouped 1/2" at 50 with 900B)
59ish barrels=field size, and 7 3/8 compensated type (don't use comp)

In other words, early barrel fits fine on later frame but won't feed. Later barrel on early frame-ditto. On their own frames they work perfect.

What I want to do is use the relined 1977 barrel on the 1959 frame.

Jack H