[Starstruck]

Hubby’s thinking about using a 22 magnum, but I’d rather just have something that would hurt just enough that they would stop coming into the yard, but not really hurt them.

A BB gun (not pellet) is effective, but I've been called out on that even though the dog was attacking one of my cats at the time. I told the owner if it happened again I would use something a little more lethal. I never had the dog in my yard again. By the way I'm not known in my neighborhood as "that guy".

[Tilted Irish Kilt]

Starstruck is correct !
When fairly close , a BB gun is an effective deterent; it stings and there is no harm.
When out some distance , a "sighted-in" pellet gun is effective when the perp is hit in the rump
When silence is valued , a "wrist-rocket" (sling shot with a marble, or marble sized projectile'stone) is effective and gets the message across.
When noise is not a concern, a 12 gague/ 410 cal. loaded with kosher salt (instead of lead) sends an audible message to the critter , the owner , and to the neighborhood !