Barrel liner questions

[Tokarev]

What would you consider the thinnest safe wall for a liner?
Example: is it safe to line a 442 grove diameter to 38 cal w/o rimming the existing barrel, or is it too thin?
And the other way - what caliber a 442 barrel can be safely lined to?

[John Taylor]

The 25-20 liner is .437 diameter, give plenty of room for epoxy. I have never tried installing a liner in a bore that I wanted to save so I don't know the answer. You would probably want to solder a sleeve on the liner that would fill the old chamber.

[AkMike]

What would you consider the thinnest safe wall for a liner?
Example: is it safe to line a 442 grove diameter to 38 cal w/o rimming the existing barrel, or is it too thin?
And the other way - what caliber a 442 barrel can be safely lined to?

Does this .442 ID barrel have a 3" Outside Diameter or a 1/2" OD. That's what matters.