I have a few lee Speeds that need new barrels & was going over my ideas of cartridge canadates with a member on this forum, thinking of 40/60 Maynard (loaded nitro) & 405 Win, maybe shortened, which he went on to do, I supplied the brass for that job also !

Seems to have been given the credit for that idea now how ever !

Any way 40/60 Maynard can be formed from belown out 303 or 30/40 Krag, no doubt 7.62X54R belown out could get you to a 45 cal, but then you may as well go to 45/70 which is almost common on the Siamese may be 45/90 is doable, 50 Alaskan is also done, your can form brass from the 348 or I'm sure Starline & others do brass for this now days !