Rimfire ammo, sorted by what you actually shoot

.22 LR is the universal standard — cheapest, quietest, and chambered in more guns than any cartridge in history. .22 WMR (Magnum) uses a longer case for roughly double the muzzle energy. .17 HMR necks the WMR case down to a .17-caliber bullet at 2,550+ fps for a dramatically flatter trajectory on varmints. The three are NOT interchangeable — each requires a firearm chambered specifically for it.

Loose-pack bulk ammo is typically the same product line as boxed versions with less packaging. Rimfire priming is inherently less consistent than centerfire regardless of packaging, so occasional failures happen with any .22 — quality bulk from major makers runs fine in well-maintained guns. If a specific rifle is picky, it's usually the gun-and-load pairing, not bulk versus boxed.

Subsonic ammo stays below roughly 1,125 fps, avoiding the supersonic crack. Through a suppressed rifle the difference is dramatic. Without a suppressor, standard-velocity .22 LR (~1,070 fps from most rifles) is already near-subsonic, so dedicated subsonic loads matter most for suppressor owners.

Rimfire priming compound is spun into the case rim, and coverage isn't perfectly uniform — that's inherent to the design. A dud that fails on one strike will often fire when rotated and struck on a different part of the rim. Wait 30 seconds before clearing any misfire, and keep the muzzle downrange.

In most revolvers and tube-fed lever/bolt actions marked for it (like the Henry Classic): yes. In semi-automatics: generally no — they're tuned for .22 LR pressure and length, and shorter cartridges won't cycle reliably and may not feed at all. Check your firearm's barrel markings and manual.