The RWS model 460 airgun (.177 cal) has a MV of 1350fps. My model 48 is supposed go 1100fps, but my chrony indicates that it is about 300fps down. This makes me believe that the mainspring has at least 1 break in it. Before I buy a new one for it, I'd like to know if the 460 mainspring is of dimensions that would allow it to be installed into a 48. I'm not concerned that the higher 460 spring pressure will probably reduce the life of other components in the 48. I just want to know if it will fit into it.