If your loaded cartridges are less than 3.08" long, magazine geometry will not compel appropriate alignment and rim jams are possible. If you have rim jams with regulation-length cartridges, something else is at play and it will probably require hands-on diagnosis by someone experienced with the US Krag feed mechanism to identify and correct the problem.

If using short cartridges, rim jams may be avoided by elevating the muzzle during loading, far enough to allow gravity to move the cartridges back against the rear wall of the magazine with sufficient energy to align the rims. If the short cartridges are of uniform length, the same effect may occur if the muzzle is depressed enough to allow the rounds to slide forward against the front magazine wall.