With Lead fouling I blew up the muzzle of the barrel on my $180 1962 Ruger semi auto 44 mag carbine.
That is common and there are no replacement barrels.
I noticed that the front of the 444 marlin chamber is the same as 44 mag.
So I got a surplus 444 Marlin barrel from Numrich gun parts corp.
Cut off the breech, drilled a gas hole, yadda yadda
0.9" 3 shot group at 100 yards with a 4X scope.
Now I have the world's most accurate and heavy Ruger 44 carbine.