66 calibers, gauges, and the stories behind them.

The smallest common centerfire — historically important and fun to collect, but modern micro .380s do its job far better.

Technically sound but fighting the market's gravity — capacity gains are modest, ammo choices thin, and 9mm's shadow is long.

A pleasant-shooting antique of a cartridge — the classic European pocket-auto round that .380 pocket pistols effectively retired.

A clever idea that shoots harder and louder than its size suggests — the extra round is real, but ammo can be hard to find and never cheap.

Serious blast and muzzle flash from short barrels, but from a lever carbine it turns into a soft-shooting brush gun — the most versatile revolver chambering ever made.

Loud, flashy, and expensive to feed — a genuinely capable cartridge that lost the institutional argument to cheap, improved 9mm.

Cartridge, Caliber .38, Ball, M41 (US aircrew issue)

Gentle from a full-size revolver and still the snub-nose standard — a century-old design that modern +P hollow points keep relevant.

Flat-shooting and soft in a heavy 1911 — a competition and Latin American market classic that mainstream American carry largely passed by.

The pocket-pistol cartridge — easy to carry, but tiny blowback guns give it more snap than the ballistics suggest, and ammo runs pricier than 9mm.

.40 S&W's snappier recoil and the FBI's return to 9mm ended its duty-era dominance, but police trade-in pistols make it one of the best used-gun bargains going.

Genuinely stout recoil that most shooters respect after one cylinder — superb for handgun hunting and bear country, less practical for high-volume range days.

A gentleman's big bore — mild to shoot and accurate, but factory ammo is scarce and priced like the specialty item it has become.

Cartridge, Caliber .45, Ball, M1911

A big, slow push rather than a snap — beloved by 1911 devotees, though 9mm's capacity and cost advantages have made .45 the traditionalist's choice.

The original big-bore sixgun round — soft-shooting in standard trim, and mind the sharp split between cowboy-level loads and the heavy stuff made for Ruger-class guns.

Recoil that ends range sessions early — a legitimate big-game revolver cartridge most owners feed .45 Colt for practice.

.455 Revolver Mk II (British service)

A gentle big-bore from another century — factory ammo exists but is scarce, and unconverted Webleys are the collector's prize.

Pure spectacle — enormous muzzle blast, ammo north of two dollars a round, and a grin on everyone at the range when the Eagle comes out.

An event, not a range gun — ammo runs several dollars a round and the recoil is a bucket-list experience most people check once.

The backcountry carry favorite — real power in a duty-size auto, though many commercial loads are watered down to near-.40 levels, so label-reading matters.

5.7x28mm NATO (standardized 2021)

Almost no recoil, 20-plus round magazines, and a flat trajectory — the trade-offs are pricey ammo and a bullet weight class all its own.

7.62mm TT (Soviet service, TT-33 and PPSh-41)

Flat, fast, and startlingly loud with a fireball to match — a collector's delight whose surplus ammo supply is drying up.

9mm NATO (M882 ball in US service)

The default handgun cartridge of the modern era — cheapest centerfire pistol ammo, mild recoil, and the widest gun selection ever offered in one chambering.

9mm PM (Soviet/Warsaw Pact service pistol cartridge)

The surplus-pistol staple — Makarovs are famously reliable, though the once-cheap imported ammo has gotten pricier as import politics shift.

The varminter's hot rod — spectacular on prairie dogs, hard on barrels, and traditionally twisted too slow for the heavy-bullet games.

A genuinely clever long-range idea whose rough launch and the ARC's rise left it a well-liked also-ran.

The classic first deer rifle — mild, accurate, and honest, provided you feed it the heavier bullets when deer are the job.

Charming and genuinely hard to shoot well — the thin patterns punish sloppy swings, which is why old-timers call it an expert's gun handed to beginners.

The goose-pit heavyweight — throws the biggest payloads going, in guns that weigh like boat anchors and shells priced like a specialty item, because they are.

Laser-flat for a rimfire and devastating on varmints, but the light bullets drift badly in wind and it's strictly a small-game number.

The hottest rimfire going, but a narrow rifle catalog and spotty ammo supply keep it a dedicated varminter's choice rather than a mainstream one.

Cheap, quiet, and nearly recoilless — the cartridge everyone learns on and nobody outgrows, though bulk-pack reliability varies box to box.