The gopher part reminds me of growing up on our small farm. There was a big rock in the corner of the property. The fence went right through it and the country road, not too far away. The marmots had eaten all the alfalfa for an acre or so around the rock and it was a low light green grass where the rest of the farm was 3 foot tall alfalfa.
I was trusted as a kid to be safe but I was allowed to engage the rodents. You could shoot safely with a shotgun quite a bit wider than you could with a rifle so for a while I shot them with the same pump gun I have now. 30" full choke reaches pretty far on marmots. But after a while it got boring and the local home hardware had ammo.
3" mag 000 buckshot and some 3" slugs soon became the shells of choice. Lets just say that 10 .36" pellets or other buckshot shells work very very well against fat marmots.
Kinda like 10 .22 shells at the same time.. ok, well a bit more like 10 9mm shells at the same time but close...
I think back .. It was fun being a kid on a farm sometimes.