They can be caught without ever digging. I have seen them on the surface in knee deep water before without digging. I would bet they come out often enough but probably don't last long if there are any fish around.

I figured I would try the 2 inch and see what happens. If I can get a clean pull and then pull it back in the hole and pull again it may work the same or close to the slurp gun. Either way it gives my kids a clam gun they can pull easily and try to help. I made a 3 inch gun but have to either finagle the caps for the 2 inch or get flat caps for it. Didn't think and got the curved caps so sealing it may be tough with them.