Has anyone here ever shot varmints with rounds that are not typically associated with varmint hunting? I have several older rifles I might try. It would add some "fun" factor to the shooting.
Oh, but, of course. My family has used a huge variety of cartridges and firearms. Some days, we'll even set rules of engagement.
Sometimes, we'll require mil-surps only; or pistols only; or only cartridges based on the 7x57 Mauser case (including all of the -06 and .308 based cartridges).
Some of the more interesting days were the "pistol", "iron sight", or "big bore" shoots.
With pistols, we often set a "single load, only" rule - if the action gets too fast paced. So, it is much more difficult to walk the fire into the target; since you have to take your eyes off the target to slide the next round into the chamber.
The "big bore" shoots mean each shooter brings the largest bore size rifle in their possession. It usually means the small end of the spectrum is .270 Win, and the large end is .375 H&H, .416 Rigby, or .458 Win (or slugs in a 20 or 12ga shotgun). It may sound like a really punishing day, but whacking a few squirrels or prairie dogs with those big bores can be amazing fun.
I've used several muzzle loaders (all .54 Cal I think), .22 LR, .22 WMR, .22 Hornet, .223 Rem, .220 Swift, .243 Win, .270 Win, 7mm Rem Mag, 7.62x39, 7.62x54R, 7.7x58 Arisaka, .30-06, .300 Win Mag, .300 H&H, 8x57 Mauser, .338 Win Mag, .358 Win, .375 H&H, .416 Rigby, .458 Win, .410 bore, 20 ga, and 12 ga. (I'm missing a few cartridges...)