I was getting many times it would fail to fire - a decent imprint on the cartridge rim - always "went off" on the second try - I must have had the thing apart 10 times to try to figure that out - might be from wear, might be from design - but this one wants a "firm", complete trigger pull for that striker to hit that rim hard enough to fire it - if you are "dainty" or try to stop your trigger pull as that sear releases, it is as if something slows down the striker enough to make it's strike to be weaker than it needs to be. It has already been too long since I had it apart - that sear rides on a rounded surface on the cocking piece, after the thing releases the striker - that "drag" appears to be enough to slow down the striker speed - and cause those misfires. So, what I have been doing with it is an aggressive trigger pull - all the way back - not a "dainty" pull as short as I can make it - and it seems to fire each time that way.
As alluded to in an earlier post - I have no clue what pressure levels these old ones were designed to handle - they were likely made (or at least designed) at a time before SAAMI existed in North America. I presume from the lower velocity that CCI Quiet are less breech pressure than other .22 Long Rifle - so I have been using those in this rifle. I have never fired less expensive "High Velocity" ammo in it, nor any "shot loads" - I simply do not know what it is capable to handle, after 100 plus years. I also have a couple of the Stevens Favourite single shot "Boy's Rifles" - the bore on one of them like this Erfurt - probably totally ignored for many decades - much rust and crap came out of them when I cleaned them - but they go "bang" and for what they are, that might be "good enough".
And there are two Stevens Favourite that were originally chambered as 25 Stevens - the both have had Redman .22 liners installed. I have never yet fired either - likely, they are about as good as those rifles could have been. It seemed to be appropriate to get an empty box for 25 Stevens Long, and another empty box for 25 Stevens Short - CIL "Canuck" brand boxes - the rifles are still stamped as "25 Stevens" on the barrel, except that round will not go into the chamber - they are .22 Long Rifle chambers now.