Help with a Mauser 1891

No, that isn't correct for a '91 or any of the Mauser actions.

Most likely what happened is that someone in the past tried to "slick up" the trigger and removed a little too much metal from either the sear or the cocking piece. This causes the cocking piece to rest too far forward...and the safety lever can't cam in front of it to engage.

The easiest patch (but not the proper fix) would be to remove a tiny bit of metal from the area I've circled on the attached photo. That's where the safety lever engages the cocking piece. This will give clearance for the safety lever to get under the cocking piece and engage the safety.
NOTE: When properly fitted the safety should cam the cocking piece off of the sear so they're not touching each other. If you remove too much metal from the cocking piece, it might let the sear drag across the cockping piece and not return to the unloaded position...which will cause the rifle to fire as soon as you flip the safety off. Do this mod at your own discretion and check your work often to make sure the safety functions properly when you're done.

The correct way to do it would be to figure out which part was modified and replace it. Most likely it's the sear.
You could also replace the factory trigger set up with an aftermarket small-ring Mauser trigger (Bold, Timney, Jard, etc...).


Also keep in mind that the old '91 is the "first of the herd" of the modern Mausers and not the safest action out there. It's missing the gas venting that later models had so if you have a pierced primer or blown case you will get a face full of hot powder gases. Also, keep your loads for it mild. Some of the data out there was developed for the 1909 Arg Mauser...which is the newer '98 Mauser pattern and much stronger/safer. (I'm assuming your rifle is still in 7.65x53 caliber)