I keep exploring the Mech Tech Carbine Conversion Unit that Jeremy S. previously reviewed here. It’s a cleverly-designed “upper” that you snap your GLOCK pistol “lower” into, converting your wundergun into a 16″-barrel carbine rifle. This particular unit converts the GLOCK into a 10mm rifle. I previously evaluated the Mech Tech with some hollowpoint ammunition for its suitability and performance as a self-defense weapon. It was impressive, sure, but I couldn’t help but think that that was the wrong path to go trundling down. Sure, it could be used for that purpose, but the bullets were overdriven so fast that they were ripped apart when the hit the gel. And that got me thinking — what would this unit be like, using some big heavy solid hardcast bullets? . . .
Fortunately, in doing the chrono testing for Jeremy’s review, I had a couple of Underwood bullets left over. Jeremy had sent some 180-grain TMJ (a generally rounded-nose projectile but with a flat face, like most .40 and 10mm FMJ’s) and some 220-grain Underwood hardcast flat nose hunting bullets. And I had some DoubleTap 200-grain wide flat nose hard casts, too.
These are not expanding bullets. These are designed to penetrate and penetrate deeply, and the flat face of the bullet does more damage than a rounded nose would. Flat-faced hardcast bullets are used for taking down big game, where you need a bullet that can smash through heavy bone structures and penetrate deeply to the vitals of a larger animal.
Now, 10mm has been used for that purpose for quite a while, from guns such as the GLOCK 20 with its 4.6″ barrel. I was curious as to just how much performance we could get from this type of ammo when fired from a 16″ barrel. Accordingly, I strung four 16″ blocks of gel end-to-end; that gave me 64″ of tissue simulant to catch the bullets. Maybe that’d be enough, maybe not, but it’s as much as I could reasonably assemble, so — I set out to blast them.
First things first; these rounds were potent. They ranged from over 900 ft/lbs of energy, to over 1,023 ft/lbs. That’s a lot of power. And yes, they penetrated very deeply in the gel — the shortest bullet I tested was the wide flatnose DoubleTap 200gr, at 50″. The Underwood 180gr TMJ went 57″, and the Underwood 220gr flatnose penetrated over 64″! I don’t know how far it would have gone as it penetrated past the end of my string of gel blocks. There’s a clear exit point so I know it made it through the block, but I don’t know how far it would have gone in an endless gel block.
Needless to say, that was pretty impressive. Getting a thousand ft/lbs of energy from a semi-auto handgun round is no small feat, and the bullets performed admirably. All the tested ammo showed substantial gains over their rated velocity and the non-deforming nature of the solid bullets means that all that energy was to work — no disintegration or fragmenting, just a big, heavy, solid mass that was pushed harder than it likely ever was supposed to, and did exactly what they should have.
This Mech Tech CCU is becoming one of my favorite GLOCK mods, and if I ever am tasked with having to take down a large dangerous animal with a semi-auto handgun, well, now I know exactly what to use to give me the best chance.
I should note that Mech Tech advises against using any Underwood ammo in their carbine conversion units, saying that they’ve been notified of overpressure situations. Please don’t take my use of it here, or in the prior test, as an endorsement to ignore the manufacturer’s warnings. Jeremy had already used it successfully and inspected all cases for any signs of overpressure issues and found none. I used the same ammo that he had previously vetted and encountered no issues.
I don’t know what calibers Mech Tech encountered problems with, but these particular boxes of these particular loadings showed no issues, so he and I felt it was safe to use. But, we took that risk on our own, against the manufacturer’s advice, so … let’s just say that it’s usually a good idea to follow the manufacturer’s recommendations and advice. Or put another way, do what they say, not what we do, and all that.