My last Tobin has a new owner. I'm likely preaching to the choir, but, low pressure loads are the key to a happy Tobin.
I'm thinking my spring vise did not fit my Tobins, and there was just enough room to compress the mains with a duck bill pliers. I can't remember if the gun was cocked, or, not when I did that, I'm guessing either way will work.

Most posts are improved with images. This was just a nice old "Tournament"
16 gauge Tobin:







Best,
Ted