I find it extremely humorous to see in threads like this the words "always" and "never". How silly.
Every gun is an individual. Your M25 may light everything while mine may not.
Case in point: My M625JM. It came from the factory and wouldn't light off Winchester primers on a consistent basis. I did not send it back. I read! Now, maybe I read too much into it but, if you go to Midway and look up JM's springs, you will see that they say to use Federal primers if you use his springs. I guess I'm just not smart enough to doubt them. I figured that they used his springs in the model named for him so, I started using Federal primers in that gun. I put in an extended firing pin too, as I do with all of my frame mounted pin guns.
I ran thousands of Federals through that gun without a hitch. Then, Federal primers got expensive and I went to Wolf primers. Again, it would only light off about 80%, same as the Winchesters. So, I took a spent primer, suggested by Joni Lynn here on the forum, and put it under the strain screw. Haven't had a problem since.
Talked to other folks, they had to do the same thing to get their JM to run consistently. They were factory stock as mine was.
FWIW