in their choices of ammo. I think a lot of them are far more picky than centerfires. Not only whether the round will cycle a semi-auto properly, but in accuracy: I've mentioned before shooting rifles that got better groups with inexpensive ammo than high-dollar target or match ammo.
What brought this up(again) is a trip to the range today. Just for the hell of it I stuck a box of the Aguila SSS in to try on a couple of rifles. This stuff is loaded subsonic and has a long, 60 grain bullet instead of the standard 40 grain. To keep the length correct they make the case short; weird looking round. And whether a rifle or pistol shoots it worth a damn depends on the whim of the gun. Some shoot it quite well, and others will keyhole the bullet at 25 yards: the rifling on many does not spin the bullet fast enough to stabilize.
I've now found two of mine that shoot it well: the Martini Model 12, which will put the things into 2.5-3.5" groups at 100 yards, and my Remington 512. At 50 yards this rifle hits dead-on with Federal Champion and gives about 1" groups or a touch better. It put five rounds of the Aguila 3.5" low and 2" right at that range, but the group- including a flyer I have to call my own- was 1.3". Take out the flyer, .7". Not bad at all.
For pests and small game this round, assuming your gun will shoot it well, ought to be a killer: with the weight and shape it should penetrate very well on larger critters. But you'd probably have to zero specifically for it, as that weight and velocity means it'll have a different point of impact than pretty much everything else.