hans: I have to agree with Gary Lamberth - I too have a Montana Rifleman 444 Marlin barrel, but on my winchester 94 Big Bore and, I love it. I feel it is a quality barrel and well made. In all my conversations with the Montana Rifleman staff I was impressed with their knowledge and sincerity. My Winnie is a beauty.
For Mr. Lamberth: talk to a fellow named Harpy - he makes some gorgeous jacketed bullets for the 444, all the way to 410 grains. From your Model 48, if your barrel is the same length as the 23" original, you should be able to take anything on this continent with some of his loads. In addition, there are a number of other folks on these forums (check the lever action forum) who load for the 444. BTW, the first 98 I ever saw chambered for the 444 was in the Bronx, in 1968. A gunsmith named 'Doc Barth' put it together and used a wormwood design on the stock. It too was a beauty.
Hope this helps. Mikey.