My .44-100 Rem St.

[Kurt]

Don. That first Organ barrel with the deep groove has a chamber cut for a PP bullet and it will not chamber a GG. The chamber is matches for a four thousand deep groove so the bullet does not upset more then the groove is deep. The deep grooves that barrel had did not let a PP bullet upset enough to fill the grooves for a good gas seal.
The replacement barrel Joe sent was also off in groove depth but this time it was on the shallow end which is beneficial for the PP bullets at three thousands deep but again checking the barrel with a slug gauge ti has loose spots in two places, not good for accuracy, but I was able to lap the barrel and get that problem solved.
For a PP bullet I will take a shallow groove over a deep. Deep grooves are good for a patched ball and the first barrel had a patched round barrel deep groove.