Found the same to be true, picked up some plinking ball ammo once and wouldn’t even load into the magazine.When I had one, I found that the issues are bullet shape, size and weight. I discovered several brands that are similar enough to the recommended ammo to function well.
Not sure of mfg date but is an original Milford modelWhen was your Seecamp made The newer ones can use other ammo.this is from their websiteView attachment 374900