I have a Benjamin Ben Franklin pistol from about 1975. I didn't know it @ the time, but I had pumped it up too far ( 20 times if I recall, only supposed to pump 12, I think), and the hammer spring was not strong enough to depress the plunger. This was in 1984. I left it in my basement until about 1992 when I decided to take it apart and fix it. I couldn't figure out what part had broke. Put it back together. Still didn't work. About a year later, I took it apart again, figuring that the plunger coming out of this cylinder must be a moving part. Tried to depress it and I couldn't. Tapped it with a hammer, no go. Finally I gave it a couple good whacks and pop it went. The plunger did depress and released the compressed air. The gun works fine today, I just can't pump it more than 13 times. 14 and there is reserved air in the cylinder. So, there you go for an older Benjamin - about 7-8 years.