The .40 somethings: often compared to one another, the cruiserweight .41 Magnum and 10mm rounds aren't truly equal but have much in common

The .41 Magnum revolver cartridge and the 10mm Auto round are often compared as equals. They aren't, but when you start looking at them, it's downright eerie how much they have in common. I

Each was originally intended for combat work, and each--the .41 in 1964, the 10mm in the late '80s--was ballyhooed as the next ideal police handgun cartridge. Each had some spectacular early adoptions (San Francisco, Amarillo, and San Antonio for the .41, FBI and the state troopers of Virginia and Kentucky for the 10mm), but neither caught fire in popularity and neither is much seen anymore in law enforcement. In both cases, an arguably exaggerated perception of excessive recoil had a lot to do with that.

Each is a flat-shooting cartridge and both retain energy well at longer distances. Each benefits from a broad power range in available loadings, but neither was introduced in an optimum cartridge format, hurting their popularity. The .41's police load was a non-expanding 210-grain lead semiwadcutter at 950 to 1,000 feet per second. It delivered reasonably good stopping power but generally shot through and through the felon, creating unacceptable danger to bystanders behind him.

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The first 10mm Auto amino was by Norma, in tandem with the Bren Ten project. The Norma hollowpoint was too toughly jacketed to open reliably, and the 200-grain, 1,200 fps jacketed truncated cone configuration was powerful enough to crack the steel of the early Dornaus & Dixon Bren Tens, and was horrendously over-penetrative. Larry Kelly Magna-Ported the extended inch of a 6" Bar-Sto barrel on my Colt Delta Elite 10mm, and shot a big wild hog with one of those Norma 200-grain JTCs. The bullet entered the front of the chest and exited the rear ham. It was a one-shot kill, but that bullet could have killed three or four men standing in line facing the shooter. By the time good hollowpoint loads had been developed for both .41 Magnum and 10mm, each caliber had lost its momentum in the race for popularity.

Both cartridges lent themselves well to carbines. The FBI still has some HK carbines in 10mm, only now being traded out for .223s, with their S&W 10mm pistols already consigned to the FBI Museum. Marlin briefly produced its excellent 1894 lever action in .41 Magnum. Similarly, each has been chambered in the type of handgun opposite what it was designed for. The .41 Mag revolver cartridge has been offered in the Desert Eagle auto, and the 10mm Auto proved deliciously accurate in the S&W Model 610 revolver.

Ballistic Comparison

At the top end, the .41 stomps the 10mm in power. It simply has more powder capacity in the case, and is chambered in stronger guns. The .41s roughly 1/100" advantage in bore diameter has little to do with it. On the factory ammo front, Winchester has offered a Platinum Tip 240-grain .41 bullet at 1,250 fps velocity generating 833 foot-pounds of muzzle energy, and CorBon a 250-grain hardcast at 1,325 fps and 975 ft-lbs. No 10mm load can safely approach that. For a hot 10mm load, the CorBon 180-grain softpoint at 1,320 fps and 696 ft-lbs roughly duplicates the old .38-40 Winchester deer rifle. Nothing to sneeze at, but not the power level the same manufacturer can offer in .41 Magnum.

The Silvertip Connection

Where the 10mm Auto does poach into .41 Magnum territory successfully is in what may be the two most street-proven anti-personnel loads in each caliber: Winchester's Silvertip hollowpoints. These bullets tend to expand rapidly with fragmentation of the expanded petals caroming off into adjacent tissues to magnify the wound channel, rather like the famous 125grain .357 Magnum JHP round. The Silvertip will hold a core of expanded projectile together at better than .50 caliber, penetrating to optimum depth. The wounds produced are impressively massive.

In 10mm, the Silvertip is one of the stouter loads available for the caliber, using a 175-grain 40-caliber projectile at 1,290 fps, creating 649 ft-lbs of energy at the muzzle. The "downloaded" .41 Silvertip sends a bullet of identical 175-grain weight out of the muzzle at 1,250 fps for 607 ft-lbs, a near-twin performance actually slightly favoring the 10mm. It is largely from this comparison that the 10mm has gained its not-quite-deserved reputation as "a .41 Magnum automatic."

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Impressive, But Uncertain

Skeeter Skelton had called for a round like the .41 in the 1950s, and so had Chic Gaylord, who actually predicted the .41 Magnum name in 1960. Elmer Keith and Bill Jordan were the ones who talked Smith & Wesson into making the guns and Remington into creating the .41 Magnum cartridge, which was finalized in 1963. The 10mm was inspired by the writings of Jeff Cooper, and by Jeff's write-ups of Whit Collins' experimentation with a similar wildcat cartridge.

Today, both .41 Magnum and 10mm Auto are "cult calibers," kept alive by serious shooters with an enthusiastic devotion to their particular ballistic niche. Revolver devotees have their fingers crossed for a Thunder Ranch S&W in .41, rather like the fine old Model 58 service revolver with fixed sights discontinued in the late '70s. Personally, to better take advantage of the wide range of load options, I'd go with Smith's sweet Model 657 Mountain Gun with adjustable sights and gracefully tapered 4" barrel.