The .45 Colt Cartridge as .45-70

by Hamilton S. Bowen


The .45 Colt Redhawk is the perfect home for the .45 RHO cartridge. It is smaller than the grand old .45-70 rifle round only in size but its moral equivalent otherwise.


The storied .45 Colt, our first truly effective centerfire handgun cartridge, was introduced in the Colt Single-Action Army revolver in 1873. Even now, a 250 to 260 grain bullet rumbling along at 900 to 1000 feet per second is usually adjudged to be an effective man-stopper. Sport hunting with revolvers was unheard of in the late 19th century, so the limitations of the .45 Colt as a big-game hunting round were largely irrelevant back then. Things began changing in the mid-1920s when Elmer Keith, the acknowledged father of modern sport revolver craft, started his quest for a serious big-game cartridge suited to the revolvers of the day. Keith abandoned the .45 Colt in favor of heavily loaded .44 Special cartridges and set in motion an evolution in big-game revolver ammunition that continues to this day. Responding to decades of crusading by Keith, Smith & Wesson got on the bandwagon in 1956 and introduced the timeless .44 Magnum in what became their iconic Model 29, a seminal event for sporting revolver enthusiasts. A couple of decades would pass before another pioneer picked up Keith’s torch and pressed on.

That pioneer was pistolsmith John Linebaugh, who saw what nobody else did at the time – that the .45 Colt would be the platform for the next leap forward. Linebaugh’s experiments in the late 1970s and early 1980s showed that the .45 Colt, housed in a strong, modern single-action like the Ruger Blackhawk and loaded with heavy, 300-grain bullets propelled to velocities of 1200 to 1300 fps would easily surpass the performance of the 240-grain .44 Magnum cartridge. Linebaugh’s high-pressure .45 Colt loadings in custom-made, five-shot guns propelled 340 to 350-grain bullets at velocities of 1400 to 1500 fps. His cartridges became the new standard by which high-performance revolvers were judged. Ross Seyfried proved the point by using one of Linebaugh’s guns to successfully duel with a Cape buffalo. Concurrent efforts by Dick Casull mirrored Linebaugh’s results when heavy bullets were utilized in the .454 Casull. Never one to sit on his laurels, John moved on to the .475 and .500 Linebaugh rounds, which to this day are still the finest ultra big-bore revolver cartridges extant, at least in the opinion of yore obt. scribe.

Flanked by the Garrett .454 Casull on the left and the Garrett .44 Magnum on the right, the three .45 Colt-based offerings, left to right: the .45 RHO, .45 LFR and .45 Colt +P.

At about the same time that Linebaugh was developing his cartridges, Randy Garrett, the founder of Garrett Cartridges, was reviving the flagging fortunes of the .44 Magnum. Garrett showed that the old classic was still in the hunt by developing cartridges that safely propelled 310 to 330-grain bullets to velocities of 1300 to 1400 fps. Garrett’s .44 Magnum rounds were perhaps not as glamorous as the .454 Casull or the .475 and .500 Linebaughs, but they became the favorites of serious hunters armed with the .44 Magnum. Now most of the big ammunition makers have cartridges similar to Garrett’s in their product lines.

Much like the .44 Magnum, the .45 Colt soldiers on in good style, in part because reloading component manufacturers recognized that the .45 could be safely loaded to moderately high pressures in modern guns. Most handloading manuals contain special sections featuring data suitable only for use in Ruger Blackhawk revolvers and Thompson Contender single-shots. Two developments made it possible to boost the performance of the .45 Colt to the next level. One was the advent of a .45 Colt chambering of Ruger’s ultra-strong Redhawk double-action revolver. The other was the succession of Ashley Emerson as the head of Garrett Cartridges after Randy Garrett retired.

My old friend Ashley Emerson is a highly experienced hunter and a world-class marksman with both rifle and revolver. When he assumed control of the Garrett firm, he took a page from his predecessor’s playbook by recognizing that the .45 Colt could be modernized in much in the same way that Randy Garrett modernized the .44 Magnum. Garrett Cartridges already offered two excellent conventional .45 loads. Emerson’s 265-grain +P Hammerhead round is loaded to around 1000 fps and is still mild enough to be suitable for 2nd- and 3rd-generation Colts and the new, midsize-framed Ruger Vaqueros and Flattop convertibles. It’s also usable in modern N-frame Smith & Wessons. Even at vintage velocities, the improved shape of the bullet yields performance dividends. His .45 LFR cartridge (LFR stands for large frame revolver) is recommended only for large-frame Ruger revolvers. It launches a 365-grain bullet at 1250 fps. Even with somewhat heavier bullets than usual, this is typical of contemporary heavy-bullet, high-performance .45 Colt ammunition operating at less than 35,000 PSI. The LFR cartridge definitely SHOULD NOT be used in the currently popular, long-cylindered handguns designed to fire both .45 Colt rounds and .410 shotshells.

The .45-70 405-grain bullet on the left with the 405, 365 and 265-grain .45 Colt bullets to the right.

Emerson wanted to take the .45 Colt cartridge to Everyman much as Randy Garrett did with the .44 Magnum, but that only became feasible after Ruger chambered the Redhawk for .45 Colt. No other production .45 Colt has sufficient cylinder length and diameter and strength to make such a leap. After considerable investment in experimentation, time and treasure, Emerson developed a cartridge using standard .45 cases and stout charges of Hodgdon H110 powder to propel a 405-grain Hammerhead-style, flat-point cast bullet to 1250 fps from a 7½-inch barrel. Even in a 4-inch Redhawk the load achieves 1150 to 1175 fps. This is astonishing performance for an affordable, off-the-shelf revolver. If the previously cited velocity figures sound familiar, that’s because they nearly duplicate the velocity of standard factory loads for the .45-70. The rifle version of the 1873 trapdoor Springfield will crack 1300 fps with the 405-grain round. In the carbine, velocity falls off to about 1100 fps. In view of the .45-70’s enviable reputation as an effective big-game cartridge, it doesn’t take much imagination to see that the .475 Linebaugh had best watch its back.

Emerson calls his new round the .45 RHO, with RHO standing for Redhawk only. Recoil of the cartridge is considerable but not obnoxious. Anyone experienced in shooting big-bore revolvers shouldn’t have any trouble with it. What they may be troubled by, however, is the standard Redhawk grip, which isn’t the best in the world at absorbing recoil. Installation of after-market grips may lead to happier results for some shooters. I’ll have to admit my biggest concern about recoil was that the heavy bullets might jump their crimp under the cumulative effect of the pounding. However, Emerson has developed a crimping regimen that includes particularized full-length sizing of new brass, then expanding and flaring case mouths, and the result is an exceedingly tough crimp that holds the bullets firmly in place. Test cartridges have survived a couple of dozen firings of rounds in adjacent chambers without showing any significant bullet movement. The earlier warning about not using .45 LFR cartridges in those .45 Colt/.410 combination guns is doubly applicable for the .45 RHO.


Change is always coming after us, whether we like it or not. Looking over our shoulders, the new .45 RHO load from Garrett Cartridges of Texas is welcome change for a change.


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