For some reason, I’ve got it in my head to convert my GLOCK 21 to shoot a wide variety of different calibers. Not that .45 ACP isn’t enough, but — well, it’s more a case of “because I can” than anything else, I guess. Last time, I fed this .45 ACP pistol some 9mm. Today I decided to plug the lightning rods into FrankenGLOCK’s neck bolts and resurrect it in a totally different caliber: 10mm . . .
10mm is a substantially more powerful cartridge than .45 ACP. While it’s not quite as big as the .45 ACP (10mm vs. 11.5mm, and about 180 grains vs. about 230) it packs a lot more energy into the cartridge. .45 ACP rounds typically deliver somewhere around 350 to 500 foot/pounds of kinetic energy; the 10mm typically starts at around 530 ft/lbs and climbs up to the 800 ft/lbs. neighborhood.
Converting a GLOCK 21 to 10mm is really rather easy; after all, the G21 is basically a .45 ACP variant of the GLOCK 20, a 10mm pistol. The frame is the same, and (as shown in the prior video) the GLOCK 21’s slide can accomodate barrels made for the G20. So … it’s almost a simple barrel swap to get the Glock 21 to 10mm.
There are a minimum of three things you have to change out to convert the G21 to 10mm: the magazine, the barrel, and the recoil spring. The magazine is the easiest part — just use a stock G20 magazine. Because the Glock 20 and 21 frames are the same, the mag fits perfectly. Note, this is also the same magazine you’d use for .40 S&W, and it’s the same one I used for 9mm.
For a barrel, I chose a Lone Wolf factory replacement barrel for the Glock 20, in stock length.
For the recoil spring, I chose to upgrade it. The slide on the GLOCK 20 is a little heavier than the slide on the 21, and with the 10mm being a more powerful cartridge, it can batter the gun if you don’t attempt to address that. Based on YouTuber MrGunsNGear’s G21->G20 conversion video, I chose a 20 lb. recoil spring from ISMI, and mounted it to a Lone Wolf stainless steel guide rod. The GLOCK 20 actually uses the same guide rod and recoil spring as the GLOCK 21, at 17 lbs., but the slightly heavier slide lets the G20 deal with the recoil a little better. With the lighter slide of the G21, a slightly stiffer recoil spring should help manage the 10mm’s stouter recoil.
I made no change to the extractor or ejector or any other parts. If you want the utmost in reliability, you may want to do so. I tested the pistol for my purposes (ammo testing) and found it to be satisfactorily reliable (i.e., I experienced zero malfunctions). If I was planning on making this a permanent change, I’d modify the extractor.
For testing purposes, I then loaded up the gun with CorBon’s 10mm DPX round, and shot a gel block with and without denim. The results were impressive. Even though this CorBon load is one of the lighter 10mm recipes, it still did fantastically well, with perfect expansion, excellent penetration, and a nicely savage wound cavity.
In the future I will be doing more 10mm tests on some of the more firebreathing rounds out there, but I can say that I was quite pleased with the results of this initial test. Recoil was increased, yes, but it wasn’t bad at all; certainly nothing like the monumental recoil of the S&W .460 XVR! The recoil was on par with a .357 magnum handgun — noticeable, and signficant, but definitely manageable.
Truth be told, I conducted the 10mm ammo testing on the same day that I conducted the .460 XVR testing. And while, yeah, the 10mm is a big boy gun, it was dwarfed by the .460 XVR. After setting off a dozen of those hand grenades, coming back to the 10mm felt like shooting a Red Ryder BB rifle in comparison. So maybe my perspective is a little skewed; maybe I’d have been more impressed by the recoil of the 10mm if I hadn’t dulled my senses on the megabeast revolver first. I’ll try to do a back-to-back recoil video between .45 ACP and 10mm next time I test some 10mm ammo.
I’m really happy with this upgrade. For minimal expense, I’ve added a new cartridge to my repertoire, and substantially upgraded the power of my full-size handgun (not only in terms of power per shot, but also in capacity, since the G20 magazine can accommodate 15 rounds of 10mm, where the Glock 21 can fit only 13 rounds of .45 ACP).
At this point, my GLOCK 21 can fire three of the major service calibers — 9mm, .45 ACP, and 10mm. And, with a simple barrel swap, I could add a few more (.40 S&W and .357 SIG, to name two). Not sure whether I’ll bother with them anytime soon though, as I’ve got my sights set on really ramping up the power game — .50 GI and .460 Rowland are on my wish list, but my next conversion will take this even further than I was planning by converting the GLOCK 21 into a 10mm carbine rifle. Stay tuned.
