Don't know what I was thinking. On a military Mauser, there is a cut in front of the bridge for the loading clip. I measured the opening on the Mexican Short action, From the back of the receiver ring to the front of the bridge is 2 7/8 inches. To the back of the loading, clip cut is 3". A standard length would be somewhat longer, but don't have one at present to measure. Max case length for the .375 H&H is 2.85" with the max overall length of a loaded round 3.600".
The pictured rifle thus seems to be the standard length. It simply cannot be told from the picture if the necessary cuts have been made for it to accept the longer cartridge or not. One other alteration which has to be made is metal has to be removed from the feed ramp. This also removes metal from behind the lower locking lug on the bolt, so has to be done with caution. In going to the magnum chambering one is increasing the intensity of the cartridge, while at the same time reducing the strength of the action. Fortunately, except for some of the last ditch wartime, 98's the standard Mauser had a high safety margin built in. The best option, of course, is for a Magnum Mauser action, but they are hard to come by & very expensive. Best option today would be to go with a Short Magnum cartridge.
