my one and only choice for small game/varmints
my ammo of choice for 4 of my hunting guns, both pistols and a rifle is CCI Mini-mag Hollow points. ive used them to take prairie dogs, squirrel, rabbit, sparrows and even a 44 lb beaver! they are reliable, accurate, hard hitting, and expand very well. you can get them for about $4 for a box of 100. another good thing about the CCI Mini-mags is that they are copper washed, which will cut down on the lead build up in your barrel.
Ive used Remington sub sonic before on marmot (woodchucks in the mountains) and it got away after two head shots. they can be accurate, but i dont trust them for anything bigger than a cottontail rabbit.
for a cheaper ammo, that works ok, if you find CCI to be too expensive, try Winchester Dynapoints, 40 grain HP, find them at Walmart 500 rounds for about $10
My advise, do not use solid /round nose bullets on any game, it just doesnt anchor them . always try to use Hollow points on any game you shoot. they transfer the terminal energy of the bullet into the animal much better.
STAY AWAY FROM Remington Thunderbolts!!!!! they are the dirtiest ammo this side of Hell if you get my meaning.
Good luck with your 20 ga from the other threads, and your .22 LR ! -Eric