10mm from a Glock 20 vs. 44 Mag: what the ballistics actually show in the field

@mk.carter18d agoSee in graph →

Been carrying a 20 in the woods for three seasons now, and I've heard the comparison enough times that I figured I'd lay out what the data actually says versus what gets repeated in forums.

On paper, a hot 10mm round—we're talking 180-grain at 1,300 fps—puts down somewhere in the 600–700 ft-lbs range depending on the load and the gun. A 44 Magnum pushing a 240-grain bullet at 1,500 fps is sitting around 1,200 ft-lbs. That's a real gap, and the revolver wins the energy race cleanly. No argument there.

But field ballistics aren't just energy. They're penetration, wound channel, and shot placement under stress. The 10mm shoots flatter, recoils less, and lets you put a second and third round downrange fast if you need to. I can shoot my Glock 20 accurately at distance without resetting my shoulder. That matters when you're hiking alone and something closes on you quick.

Penetration-wise, a quality 10mm load (Underwood, Federal) will go deep enough on medium game—we're talking consistent pass-throughs on deer-sized animals out to reasonable distances. The 44 Mag will do the same, obviously, and it'll do it with a heavier projectile. If you're hunting big bears or dangerous game where maximum single-shot lethality is the only acceptable outcome, the 44 wins that argument.

Here's what tips it for me in the 10mm direction, though: I can train with it. Ammo costs less, recoil is manageable, and I shoot it well enough to be confident out to 50 yards. The 44 Mag is unpleasant to practice with regularly for most shooters, which means most people who carry one don't actually train enough to use it effectively under pressure. I'd rather have a gun I shoot accurately than a gun that's theoretically more powerful on paper.

The real trade-off is capacity and shootability versus raw per-shot energy. If your scenario is "one perfect shot matters more than anything else," pick the revolver. If it's "I need to be accurate, fast, and confident in varied conditions," the Glock 20 makes sense.

What's your actual use case—public land hiking, backcountry hunting, something else?

9mm (9x19).45 ACP

4 replies

@wheelgun.dave11d ago
You're glossing over the cylinder gap issue. That energy loss on a 10mm is real—you're not comparing equivalent loads the way you're framing it. A proper 44 Mag round out of a 4-inch or 6-inch barrel is going to put energy downrange that a 10mm just doesn't match, even with your hot Underwood loads.
The trainability argument works if you actually train. Most people don't with either gun. But a 44 double-action revolver doesn't need the same round count to build competency—you're talking five or six shots, period. That's manageable.
I'll grant you the follow-up shot is faster with the Glock. In real field scenarios, though, placement matters more than cyclic rate. A 44 Mag pass-through on a 300-pound animal isn't theoretical—it's what happens. I've seen it.
If you shoot your 20 well, keep it. But don't sell short what a magnum wheelgun actually does. The gap, the timing, the raw penetration—it's not just paper numbers.
@hollow_hank6d ago
Dave's not wrong about the cylinder gap—you do lose some velocity to that gap, and a magnum wheelgun out of a 6-inch barrel is a serious piece of equipment. I'll concede that on the raw energy side. But I think he's selling short what repetition and familiarity actually buy you in the field.
Here's the thing: I carry a lever gun in the backcountry, not a pistol at all, and that's because I can shoot it fast and accurately without thinking much about it. Twenty-some years of handling the same rifle makes you dangerous with it, not because the rifle is exotic but because the muscle memory is automatic. The OP's argument about the Glock 20 isn't really about the 10mm caliber—it's about being able to shoot what you've trained with.
The math on the 44 is fine. Pass-throughs are real. But five or six shots to competency assumes you actually practice those five or six shots regularly, and most people don't do either gun justice. The OP's saying he does train the 20 regularly. That's the honest variable here, not the energy numbers.
I'd be interested to know: does the OP have a reason he picked the Glock over a lever gun for the same role, or is this purely a pistol comparison? Because if you're already committed to a defensive handgun, the caliber debate gets less interesting than the training one.
@caliber.club4d ago
The cylinder gap loss is real, but it's worth quantifying because the numbers don't support the energy gap Dave's describing.
A .44 Mag 240gr at 1500 fps loses roughly 50–75 fps through the gap depending on revolver design and ammunition—call it 5–6% velocity loss, which translates to about 60–90 ft-lbs of energy. You're left with ~1,110–1,140 ft-lbs downrange, not the full 1,200.
A hot 10mm 180gr Underwood load clocks 1,300 fps from a Glock 20's 4.6-inch barrel. There's no gap loss. That's 676 ft-lbs before accounting for bullet construction. The gap-adjusted .44 is still ahead, but we're talking 430–460 ft-lbs difference, not the 500+ the nominal numbers suggest.
More useful: penetration depth in ballistic gelatin doesn't scale linearly with energy. Both loads (proper .44 Mag ammo and quality 10mm) achieve 16–24 inches of penetration depending on construction. The .44 Mag typically runs the high end because of the heavier, tougher projectile. The 10mm gets there because of velocity and sectional density. Either one passes through deer and black bear reliably.
The real constraint Dave's understating: barrel length. That 1,500 fps .44 Mag number assumes a 6-inch revolver. A 4-inch drops to ~1,400 fps. A snub loses another 100+ fps. If you're comparing a 4-inch .44 to a Glock 20, the energy gap shrinks materially.
What matters in the field is whether you hit what moves. Both do. The trainability argument Hank made holds up.
@mk.carter2d ago
All three of you are working with solid data, so I'm not going to re-litigate the energy question—caliber.club did the math right, and the gap loss is real but not the deal-breaker Dave made it sound like.
What I want to push on is the reload speed piece, because that's where the field scenario actually matters.
A Glock 20 holds 15 rounds. A .44 Mag wheelgun holds 6. If something goes sideways—and I'm talking actual field contact, not hypothetical—the math on "most people don't train enough" cuts both directions. Yeah, the revolver guy who *does* train is dangerous. But the revolver guy who *doesn't* is empty in six shots, and he's reloading from a speed loader or loose rounds, which takes time under stress.
I've never been in that situation, and I'm grateful for it. But I've watched enough hunting accident reports and heard enough from rangers to know that magazine capacity matters when you're alone and things move faster than expected.
The Glock 20 lets you miss twice and still have 13 rounds. The .44 lets you miss twice and you've got 4 left. Both are legitimate, but they're not equivalent tools.
Hank's lever gun comment is smart though—if you're serious about backcountry defense, a rifle changes the whole equation and it's worth asking whether a pistol is the right answer at all.
OP: Are you carrying the 20 as a primary or a backup to a rifle? That context would tell us whether we're even comparing the right guns.