A person can weigh a hammer then use it to test pan tension.
As for my own traps, I don’t like a floppy pan for beaver. I don’t measure what mine are set at, but they’re probably 5 lbs or so. Pretty heavy. Also, if I’m setting a foothold for a beaver, there’s a good chance it’s where they’re stepping out of the water, so 5 lbs of tension is nothing for them to fire.
If you can either quickly or quietly switch out shells, you can bring home almost anything. --JA