in all case you have a new gun and don't know the cartridge its chamber cast time. use sulfur or cerro safe or something other that works and slug the barrel, the .45 round ball may be good for the job. I you havn't done this before ask you gunsmith or somethink who knows. I believe this firm still exist in belgium, make a try with google. if the 450NE fit the chamber be careful, allways the chance that this gun is only made for the 450BPE. Same case but different pressure.