NICE thing about this conversion is that you can load up .30-30 and use POINTED bullets.
Generally, also, you can seat the bullet 'WAY out.
Makes for "extended-range" .30-30 ammo at very reasonable pressures.
SOME of these were converted by butchering the original barrels, others seem to have been done with chamber inserts. I have one here which was done with a chamber insert. The barrel was removed, insert put in place and then the barrel threaded back on, trapping a very thin flange into place. I am wondering what the original chamber is like UNDER the insert, if it can still be used. Swiss 7.5 casing has a LOT more capacity.
Any .30-30 rifles I have seen also have had the original 3-groove barrels shortened a lot, so no possibility of restoration.
Too bad: they are beautifully-smooth actions.
Do have fun!