444 was a factory chambering, Bill.
After having ran around with some guys in the TCA, I am 99.99 percent sure that TC never offered or made a 444 Marlin barrel.
I could make a quick phone call but doubt he is home or even in country.
It is all on pressures and thrust. They actually had factory chambers 7BR barrels. All kinds of warning use factory ammo only, sure I will run to the store and grab a box,lol.
They chamber the 45-70 and say it is OK? Most and I say most 45-70 ammo is pretty soft.
I have seen one factory chambered 6PPC barrel also.
As Bill mentions, screw holes for scope are scarey close to the chamber on these.
Virgin valley now MGM chambered the short mags for a while in the Encore. They started cracking across the top in line with the scope screws.
I have seen a lot of questionable chamberings in TC's in years past. 30-40 Krag, 250 Savage, 356WW were some pretty common ones. Then came the 7.62x39. That cartridge wrecked a lot of frames by folks that didn't have a grasp on things.
I won't name names, but I have a price list with chamberings offered for Contender barrels with a lot of very questionable chamberings. Advise was to load way down. Reason was to clean up bad throats and chamberings.
When this is brought up in discussion at certain places, it disappears suddenly.
Some were even short chambered so factory cartridge would not let action close. The party modified dies in order to "fix" this.
Jeff