Sauers, Merkels, and Simsons have all been used in conversion guns, I'm just not sure about the 450 Nitro cartridge. All three of these companies used the same frames at one time at least, they were made up in the Merkel factory and a virtually identical. I don't think you will have any trouble with the fames giving way as long as they are in good shape when you start your conversion. I did a .405 conversion on a Simson and it is holding up very well and I am getting ready to do a 45-120 on a Merkel. I think the 45-120 could be loaded up to 450 Nitro pressure levels in a modern gun, but I won't be loading this one that heavily. Bob