.45 Colt Ammo

What is .45 Colt?

.45 Colt (officially SAAMI “.45 Colt,” though commonly called “.45 Long Colt”) was introduced in 1873 for the Colt Single Action Army revolver — the gun that became synonymous with the American West. It’s one of the oldest American cartridges still in regular production, predating smokeless powder by two decades.

The original blackpowder load pushed a 250-grain lead bullet at ~900 fps — impressive for 1873. Modern smokeless loads can do much better, but the cartridge’s age creates a critical complication: old and replica revolvers are pressure-limited, and modern hot loads can destroy them.

The pressure warning you must read before buying

.45 Colt operates on two distinct pressure tiers, and confusing them can destroy a revolver — or injure you.

Standard pressure (~14,000 PSI SAAMI): Safe in all .45 Colt revolvers: Colt Single Action Army, Italian replicas (Uberti, Cimarron), Ruger Vaquero, lever-action rifles. These loads push 250gr bullets at ~850–950 fps. This is what you want for cowboy action, general carry, and any vintage or replica gun.

“Ruger Only” / +P (25,000–30,000 PSI): Only safe in the Ruger Blackhawk, Super Blackhawk, and similarly heavy-frame single-action revolvers specifically rated for these loads. These loads push 300gr hard-cast at 1,200+ fps. They’re powerful enough for elk and bear at close range. They will damage or destroy Colt SAA revolvers, replicas, Ruger Vaqueros, and lever-action rifles.

“Ruger Only” on the box is a safety designation, not a marketing claim. Manufacturers use it because firing these loads in the wrong gun is dangerous.

If you’re buying a lever-action in .45 Colt (Henry, Marlin, Winchester), use standard pressure loads only.

Ballistics by pressure tier

From a 5.5” barrel:

The Ruger-Only loads transform the .45 Colt from a mild historical cartridge into a legitimate hunting load. With 300gr hard cast at 1,250 fps, you’re in .44 Magnum territory from a 6” barrel.

Cowboy action shooting: what you actually need

SASS rules require:

• Lead bullets (no jacketed)
• Rifle caliber bullets at ≤1,000 fps muzzle velocity
• Pistol cartridges at any velocity, but the culture favors mild loads for speed

250gr LFP at 750–800 fps is the cowboy action sweet spot — soft recoil, clean function in SAA revolvers, and meets all power factor requirements. Black Hills Cowboy loads are the competition standard: consistent, clean-burning, and spec’d for SASS use.

.45 Colt vs. .45 ACP

These are completely different cartridges that share a bullet diameter (.452”). They don’t interchange.

Some revolvers (Ruger Redhawk, certain S&W models with moon clips) chamber .45 ACP alongside .45 Colt, but these are purpose-built for the dual capability.

Brand guide

Black Hills Cowboy 250gr LFP — the cowboy action standard. Consistent, clean, SASS-spec. ~$0.65–0.90/rd.

Fiocchi 250gr LFN — reliable practice and general-purpose standard-pressure load. ~$0.50–0.75/rd.

Hornady Custom 225gr FTX — FTX polymer tip, higher velocity than classic lead loads, suitable for hunting from standard-pressure guns. ~$0.90–1.30/rd.

Buffalo Bore 300gr Hard Cast (Ruger Only) — the hunting/woods carry load for Blackhawk owners. Full power, deep penetration. ~$1.10–1.50/rd.

Underwood 325gr Hard Cast (Ruger Only) — maximum weight, maximum penetration. ~$1.20–1.60/rd.

Sellier & Bellot 250gr LFN — European manufacture, affordable, consistent. ~$0.48–0.70/rd.

Price guide (2025–2026)

Firearms chambered in .45 Colt

Single-action revolvers:

• Colt Single Action Army — original and current production; use standard pressure only
• Ruger Vaquero — modern design, standard SAA dimensions; use standard pressure
• Ruger Blackhawk — the only common single-action rated for “Ruger Only” loads; 5.5” and 7.5” barrels
• Uberti, Cimarron replicas — beautiful Italian-made SAA clones; standard pressure only

Lever-action rifles:

• Henry Big Boy .45 Colt — most popular current lever-action; standard pressure only
• Marlin 1894 Cowboy (now Ruger-made) — standard pressure only
• Winchester Model 1873 replica (Uberti) — standard pressure only

Multi-caliber revolvers:

• Taurus Judge — also chambers .410 bore shotshells
• Smith & Wesson Governor — also chambers .410 and .45 ACP