Problem With Osborne Strap End Punch

[Modad2010]

A couple of months ago I finally bought a 1 1/2" Osborne English point strap end punch for making gun belts. A couple days later I broke a finger that put leather working on hold. Recently, I finally got back to the bench and made a double thickness belt ( 2 layers 8oz.) - punch worked great. Tonight I was punching another belt and part of the right side of the punch buckled and bent. There was nothing under the leather but my cutting board that was placed on top of my granite slab. I am really disappointed about this. Has anyone else had anything similar happen? I have a 1" round strap punch and an 11/2" oblong punch - both Osbornes and have had no problems.