Hello Masteriflerman.......The .30/30,.38/55 cartridge bases are much smaller than the .45/70,.38/56 bases. Ejection port, loading port,bolt face, and more are sized for the larger cartridge. (won't work) Take CareMasterifleman said:Are you sure you want to do that to the 1895CB you have? You might want to get a common 336 and have Marlin do a Cowboy Conversion ($285) on it and then have it re-chambered. It might be a cheaper proposition in the long run.