Good question. I went to Marlins web-site. All they displayed was a 45/70 and did not mention any other caliburs. This 45/70 did not have a ported barrel. But I have seen 450s ported but don't know if they still make them. Barrel length was 18.5 inches. I think my son-in-law has a 44 mag 1895G. I thought they also came in 444 and 45 LC. But now, from their web-site,it looks like they are only made in 45/70. ???