Used to have a good deal of trouble with getting gopher traps buried. I tried most all the traps mentioned above and found the the Cinch trap was the best but still got buried or pinched the gopher and made them smart to the traps. A couple of years ago I tried Trapline's Gophenator trap. It did not do any better. The problem was more pull outs then anything else with the Trapline trap.
Our gopher, the Camas Pocket Gopher, is on an average larger then the other species in the country. The second picture is a pretty large one and most will be several ounces less but there size is the main problem. The Trapline trap when modified as the first picture shows is the best of the best. I set fresh open holes and cross tunnels with them. The main things to remember when setting is first only set in a narrow part of the tunnel where the trap jaws are touching the sides of the tunnel. Second and maybe more important is to bed the trap very solidly. If I set a open hole I make sure the trap is as far from the opening as I can possibly get it and I close the opening down a bit. Cross tunnels are set in narrow spots even it I have to dig a ways to find them/ Sometimes I can leave the tunnel open but if not I plug both ends as far from the traps as possible.
The modification I do is simple. The trap comes with the ends of the jaws tipped in a bit. I heat that tip, a propane torch will do this, and bend them in at ninety degrees. I them sharpen the bends. Then sharp tips are what does the trick on the bigger ones that used to pull out. I also bend the jaws out considerably so I can set a bit wider tunnels.