Guns and Gear

The venerable .45 Colt

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By John Barsness, GUNS Magazine

The .45 Colt appeared in 1872, a cooperative venture between Colt’s Patent Firearms Manufacturing Company and Union Metallic Cartridge. The next year it became the official handgun round of the US Army, chambered in the Colt Single Action Army revolver.

Most original civilian and military black-powder loads used 230- to 255-grain bullets and 30 to 40 grains of black powder, producing around 850 to 900 fps depending on barrel length. The case was of “balloon head” design, relatively thin brass folded into a narrow rim like those on rimfire cartridges. These held more powder than later machined or extruded cases with solid brass surrounding the primer, but weren’t as strong.

Groove diameter of original revolvers was as much as 0.457 inch, to allow reasonable accuracy even when fouled with black powder. Bullet diameter and cylinder chamber mouths measured as small as 0.452, but soft lead bullets bumped up to larger diameter easily when they entered the bore. (This disparity between bullet and bore diameter was fairly common in black powder days. Just ask anybody who’s ended up with an old .40-82 Winchester.)

Even into the second half of the 20th century some new .45 Colt revolvers had smaller cylinder mouths than bore diameters. Many shooters wanted to use hardcast or jacketed bullets, which wouldn’t bump up, so accuracy suffered.

Only in the past few decades have modern revolvers been standardized with chamber mouths and barrel groove diameters of right around 0.452. This made .45 Colts more versatile, since .45 ACP bullets also work. The 185-grain Hunting Shack cast bullet and 230-grain Sierra listed in the loads are actually designed for the ACP. They don’t have crimping grooves, so were crimped at the front of the cylindrical portion.

Long after the manufacture of balloon-head cases ceased, common wisdom insisted .45 Colt cases are weaker than those of other modern rounds. The manager of a local gun store and I got into a discussion about this a few years ago. He insisted .45 Colt brass was so thin “if you load it up to .44 Magnum velocities the cases only last two shots.” I didn’t argue the point, instead going home and sectioning a few .44 Magnum and .45 Colt cases. The heads of both .44 and .45 Federal brass measured 0.175-inch thick, while Winchester .45 Colt brass was actually thicker than Winchester .44 Magnum brass, 0.193 to 0.169-inch. I showed him the sectioned cases and he thanked me for the enlightenment.

The limiting factor in .45 Colt pressures today is the revolvers. Colt still manufactures the Single Action Army in .45 Colt, with a couple of time-outs since 1873. Today’s SAA is made of stronger steels, but still has relatively thin cylinder walls, and the same is true of the many clones of the SAA.

Other .45 Colt revolvers such as the Ruger Blackhawk and Freedom Arms are much more robust. This is why handloading data includes loads at a maximum of 14,000 CUP/psi (the SAAMI standard), plus data for Rugers and other firearms capable of withstanding much higher pressures.

Please note the dual CUP/psi designation. CUP stands for Copper Units of Pressure, obtained in a copper-crusher test barrel. Today psi stands for pounds per square inch as measured either in a piezo-electronic test barrel or by strain gauge. You may have heard CUP and psi aren’t the same. While that’s true at higher pressure, at low pressures they coincide.

There’s no SAAMI accepted standard for higher-pressure .45 Colt loads, the reason all .45 Colt factory ammunition from major manufacturers adheres to the 14,000 limit, with 225- to 250-grain bullets at 750 to 960 fps. Some ammo from smaller factories can be listed as +P so should only be used in stronger revolvers.

Many (but not all) powder and bullet companies also feel confident enough in the brain-power of handloaders to list higher-pressure data, but their own maximum limit varies, and few list pressures. Accurate Arms and Ramshot (both owned by Western Powders) data maxes out at around 29,000 psi, though most Accurate powder loads are in the 20,000 psi range. The top Hodgdon loads are around 30,000 CUP or psi.

The informal 30,000 rating for heavy-duty .45 Colts enables it to match .44 Magnum velocities with bullets up to about 250 grains, even though the .44’s maximum SAAMI pressure rating is 36,000 psi. The larger bore and powder capacity of the .45 provide a ballistic advantage, but with bullets of 300 grains or so the .45 doesn’t quite keep up.

Some older gun writers offered a third category for modern Colt SAA and other revolvers with thinner cylinder walls. Elmer Keith’s favorite “full power” .45 Colt load for modern Colt SAA’s was 18.5 grains of 2400 and a 255-grain cast bullet—and Alliant doesn’t offer two levels of data. Their maximum 2400 load for Speer 250-grain bullets listed is 15.4 grains.

Keith emphasized not relying totally on a hard crimp for heavy .45 Colt loads. He said the case neck itself had to grip the bullet firmly, to insure consistent burning of slow-burning powders. He also didn’t like magnum primers with any cast-bullet load, even with slow powders, suggesting hotter primers tended to melt the base of the bullet. I’ve found wisdom in everything Elmer Keith wrote about revolvers: The listed loads used CCI or Federal magnum primers only with slow powders and jacketed bullets. My RCBS dies also provided a very firm grip on all the bullets.

There are examples of the two main types of modern .45 Colt single actions in our house. My wife Eileen has a Beretta Stampede SAA clone, made by Uberti, she won in a drawing at the SHOT Show several years ago. The thinnest cylinder wall measures 0.065 inch, and the cylinder mouths measure 0.453. The thinnest of my Ruger Blackhawk Bisley’s cylinder walls measures 0.093 inch, and the cylinder mouths 0.4215. The groove diameter of both barrels is just under 0.452 inch.

Other differences are the much heavier topstrap on the Ruger, and a longer cylinder, allowing heavier bullets to be loaded. It’s easy to see why the Ruger can handle much higher pressures.

I’ve owned several Ruger .45 Colts over the years, including the 4-5/8-inch-barreled model carried for several years as my backwoods gun here in Montana. Eventually I decided a double-action was more practical for that use, and bought a stainless .44 Magnum. The short-barreled Ruger was replaced by the Bisley, used strictly as a hunting revolver. Next to our small town is a wildlife management area only allowing shotguns, muzzleloaders and “traditionally chambered” handguns. It’s crawling with whitetails, but also a few moose, and someday I’m going to actually draw a moose tag after 30+ years of trying, and Bisley a Bullwinkle.

The .45 Colt is also informally known as the “Long Colt,” to differentiate it from the .45 ACP. This drives many purists crazy, but doesn’t bother me much, since even some professionals don’t know the difference. When Eileen won the Stampede a major ammunition company offered to send us some ammo. It arrived several days later—several boxes of hardball .45 ACP.

Alliant Powder
P.O. Box 6, Radford, VA 24143
(800) 276-9337

Hodgdon Powder Company
6430 Vista Dr., Shawnee, KS 66218
(913) 362-9455

Hunting Shack
4406 Rathbun Ln.
Stevensville, MT 59870
(800) 856-2857

Western Powders, Inc.
(Ramshot, Accurate Arms)
P.O. Box 158
Miles City, MT 59301
(406) 234-0422

Sierra Bullets
1400 W. Henry St.
Sedalia, MO 65301
(660) 827-6300

Speer Ammo
2299 Snake River Ave.
Lewiston, ID 83501
(208) 746-2351

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