Welcome to Adiga Armory! While we generally try to steer clear of doing opinionated, controversial comparison topics on calibers, we felt that the hardy .41 Magnum deserved its day in court. The following presentation may not be for the faint of heart… especially if you love the 10mm Auto like we do, but live with the assumption that it gives you “.41 Magnum power in a semi-auto”. Being that we are long-time, die-hard fans of the 10mm Auto cartridge, we have always been curious where the 10mm = .41 mag notion originated, having heard the comparison thrown around for years by all sorts of folks; from average Joe’s on Internet comment sections, to gun shop staff, to the most highly-respected gun writers and industry experts out there.
While our steamy bromance with the 10mm Auto has flourished over the years, we do like to “keep it real” with our expectations. That said, we have yet to find any data to support the 10mm = .41 Mag comparison. On the contrary, when comparing the two, they were not even close… unless of course you compared the most powerful 10mm load to the weakest, powder puff, starting load in .41 Magnum, which is a far cry from a real-world comparison. Lets start by taking a look at the load data for Accurate #9 pistol powder, as the 200g XTP over 12.5g of #9 has been our go-to 10mm defensive load for about a decade now. Not surprisingly, #9 is also a fantastic powder for rolling your own .41 Mags.
The published velocity of this load is 1170 feet per second [fps] and 608 foot/pounds [ft/lbs] of energy from a 5″ barrel. However, out of a 4.6″ Glock 20 barrel, real-world velocities of this load are around 1120 fps and 557 ft/lbs at the muzzle. Conversely, a 200g bullet over 16.9g of #9 in .41 Magnum has a published velocity of 1503 fps and 1003 ft/lbs from a 10″ test barrel. This yields a real-world velocity closer to 1350 fps and 809 ft/lbs of energy in a 5″ revolver. If comparing 5-inch barrel velocities, this constitutes a 15% increase in velocity and a 33% increase in muzzle energy.
Now, you might be saying “how about hot-rod 10mm loads from companies like Double-Tap or Buffalo Bore… those will put me in .41 mag territory”. Well, not exactly… you see, everything is relative. The .41 Mag can also be hot-rodded to attain “ludicrous speed” velocities. And, when comparing hot-rod loads side-by-side, the disparity between the two cartridges becomes even wider. Lets take a look at Buffalo Bore’s awe-inspiring heavy “Outdoorsman” line as an example.
The 220g cast lead 10mm load produces an impressive 1140 fps out of a 4.6″ Glock 20 barrel. That is 635 ft/lbs of energy at the muzzle. Very nice to say the least! However, the Buffalo Bore 230g cast lead .41 Mag load produces a massive 1370 fps out of just a 4″ revolver, or a 20% increase in velocity with a 10g increase in mass. That equates to a whopping 959 ft/lbs of energy, or a 51% increase over the comparable 10mm load.
Based on this hot-rod comparison, a .308 Winchester is ballistically closer to a .300 Weatherby Magnum [the granddaddy of .30 cal magnums] than the 10mm is to the .41 Mag. When looking at standard, 180g .308 Win and .300 Wby Mag loads, we find a roughly 1096 ft/lbs [or 38%] difference in muzzle energy. In other words, it becomes a big stretch of the imagination to say the two are producing “similar” results. Yet somehow, the 10mm Auto is assumed to be on par with the .41 Mag, despite a potential 51% increase in power from the .41.
A more accurate comparison would be to par the 10mm Auto to a full-house .357 Magnum in a 5″-6″ barrel. As you can see, the .357 Magnum produces ballistics that more closely compare to the 10mm Auto. Having said that, 10mm fans should not feel down and blue. The .357 Mag is arguably one of the best man-stoppers in the handgun world. And, with the right load, it makes a very capable backwoods defense cartridge. Having 15+1 rounds of .357 Mag power in a semi-auto G20 is nothing to feel short-changed about.
Using the aforementioned Accurate #9 load data, we can see that the 180g XTP over 12g of #9 in .357 Mag produces a respectable 1202 fps, or 578 ft/lbs of energy from a 6″ barrel. The same 180g XTP load with 13.5g of #9 in 10mm produces 1242 from a 5″ barrel, and 617 ft/lbs energy. This is only a ~3% difference in velocity and a ~7% difference in muzzle energy. Unlike the 10mm to .41 Mag comparison, these results are close enough to be considered truly negligible.
Again, if we compare the hot-rod loads from each caliber, we see that the .357 Magnum can also be “rodded” pretty hot, causing another disparity with the 10mm to develop.
The 180g .357 Mag Buffalo Bore “Outdoorsman” load produces 1398 fps from a 5″ revolver, or 781 ft/lbs of energy. The similar 220g 10mm “Outdoorsman” load pushes 1140 fps out of a 4.6″ Glock 20 barrel, for a solid 635 ft/lbs of energy at the muzzle. In this scenario, the .357 Mag displays a 22% increase in muzzle energy, but also has a 40g decrease in bullet mass as well as decreased sectional density [SD]. While significant in terms of increased energy, the drop in bullet mass and SD means they are still in the same ball park when it comes to actual terminal ballistic performance.
While we only covered a small portion of the available load data for these cartridges, it gives us a glimpse into what is quite apparent across the ballistic spectrum; that the 10mm Auto is not equal to the .41 Magnum. Perhaps the old saying “A Lie Repeated Often Enough Becomes Accepted Truth” holds firm.
Perhaps someone, somewhere, at sometime, in some long lost 1980’s marketing pitch stated that “the 10mm Auto will put .41 Magnum power into a semi-auto platform”, and it was repeated and parroted enough times that it became the “truth”. Who knows? While not everyone will be disillusioned by the data presented, it certainly ought to make food for thought. Either way, we didn’t want our love for the 10mm to blind us into believing it is something its not.
That said, we would love to hear your opinions on this subject. Thanks again for visiting Adiga Armory. Have fun and stay safe!