Shotgun Loads for Groundhogs

I have been hunting groundhogs successfully (mostly) for the last two years
on farms in PA and MD with rifles. A dairy farm in a county in PA is overrun with
groundhogs but it is in a county with a local ordinance that only allows shotguns.
I tried buckshot with my 20 ga. Mossberg 500 pump, but I am mostly missing and I don't know why ( around 50 yards). I don't have much experience with shotguns. Has anyone hunted groundhogs successfully with shotguns, and with what gauge and shotsize and target distances. Your replies will be most appreciated.

Welcome to Gunloads thlibka.

I would try some regular #4's. I also prefer a rifle, but necessity has forced me to use my 20ga shotgun on them before. (Could you possibly be able to use a .22? They aren't very loud and depending on the wording of the local ordinance, you might be able to use a rimfire if the ordinance is intended to limit deer hunters. Ask the local game warden. He might even be able to give you special permission for pest control purposes. It never hurts to ask.) Anyway, birdshot (#8, #7.5, #6) is useless beyond 25yds or so as it won't retain energy to kill cleanly. I have used #4 buck, but the patterns are too open beyond 40yds or so. Regular #4's (goose shot) seems to give the best pattern density at 50-60 yds while still retaining just enough energy to do the job cleanly. Two fast shots helps, too. Tree stands don't help - they're used to looking up for hawks, but sitting by an open window or hay door on a second or third floor can work well as they are not so used to threats from buildings. Traps (either cage or regular) can work when baited with shredded cabbage & carrots. You might even be able to place some bait in a good location to lure them into effective shotgun range.

Thank you very much for your response. I will try the #4 shot and also follow your suggestions on checking the exact wording of the ordinance to see if I could still use a rifle. (I have used my 17HMR Savage very effectively up to 100 yds at farms where I thought the neighbors might complain about "loud" shooting. (But the shotgun seems even louder to me)?)

Wtf????

Dead Spammer, gone now.