10 mm Auto vs. .40 S&W – The Heavy-Hitter Cage Match You Actually Care About

Quick-Look Spec Sheet	10 mm Auto	.40 S&W
Typical bullet weight range	135 – 220 gr	135 – 200 gr
Factory-loaded muzzle velocity (common duty loads)	1,050 – 1,350 fps	950 – 1,130 fps
Factory-loaded muzzle energy	550 – 775 ft-lb (Underwood 155 gr XTP: 775 ft-lb)	360 – 510 ft-lb (Federal HST 180 gr: 408 ft-lb)
SAAMI max pressure	37,500 psi	35,000 psi
Parent case	–	Shortened 10 mm
Same-size-frame duty gun example	Glock 20 Gen5 MOS (15+1 rds)	Glock 22 Gen5 (15+1 rds)
Felt recoil in similar-weight guns (subjective)	~7–9 ft-lb, “.357 Mag-class” snap	~5–6 ft-lb, midway between 9 mm & .45
Typical street price per 50-rd FMJ (June 2025)	$29–$42	$20–$28
Typical barrel length for energy quoted	4.5–5.0″	4.0″

TL;DR for Skimmers

The 10 mm Auto is the decisive winner if you want magnum-level punch in an autopistol, woods-defense credibility, and hand-loading headroom.
The .40 S&W still reigns where controllability, duty-size guns, and cheap training ammo matter. If you’ll never push past two-legged threats under 25 yards, or you need a slim-frame CCW that prints like a 9 mm, the .40 delivers 75 % of the energy with 65 % of the recoil—hard to hate. Serious bear country? Hot 10 mm or bust.

“The 10 mm was conceived as the flat-shooting, deep-striking answer to autopistol mediocrity.” – Col. Jeff Cooper, circa 1986
“.40 S&W bridged the capacity gap between 9 mm and .45, and it still does exactly that.” – Massad Ayoob, firearms author & trainer

Below, you’ll find a ruthlessly opinionated, data-driven comparison of these fraternal twins. We’ll look at ten battlegrounds—ballistics, real-world terminal results, shootability, gun platforms, ammo economics, and more—so you can stop doom-scrolling and start buying.

Genesis Stories—Why They Exist at All

	10 mm	.40 S&W
Birth	1983, Dornaus & Dixon/Norma/Bren Ten partnership to deliver Cooper’s “.40 cal Magnum” in a 1911-like pistol.	1990, Smith & Wesson + Winchester shorten 10 mm 2 mm so it fits 9 mm-size frames after FBI agents hated full-house 10 mm recoil.
Early adopters	FBI HRT (briefly), elite European LE, Alaska bush pilots.	Every U.S. police cruiser from 1995 to 2015, plus millions of CCW carriers.
Current trend	Resurgence thanks to Glock 20/29 Gen5, SIG P320-XTEN, S&W M&P 10 mm, and boutique ammo hitting 750 + ft-lb.	Stabilized niche: agencies leaving for 9 mm, but civilian shooters scooping up used LE pistols at bargain prices.

Verdict: The 10 mm’s comeback is real; market availability is at a 20-year high. .40’s golden age is past, but that means deals.

2. Raw Ballistics—Energy, Velocity & Momentum

Example Full-Power Loads (5″ barrel for 10 mm, 4″ for .40):

• Underwood 10 mm 155 gr XTP: 1,500 fps, 775 ft-lb
• Underwood 10 mm 200 gr XTP: 1,250 fps, 694 ft-lb
• Federal HST .40 S&W 180 gr: 1,010 fps, 408 ft-lb

10 mm routinely doubles 9 mm energy and exceeds .357 Mag from a 4.6″ barrel; .40 clusters between hot 9 mm +P+ and mild .45 ACP +P. If your metric is kinetic joules per shot, 10 mm wins by ~70 %.

Opinionated take: For dangerous game under 400 lb—a black bear sow, a boar hog—400 ft-lb isn’t enough margin. Physics beats anecdote; choose 10 mm.

3. Terminal Ballistics—What Happens in Gel & Meat

• Penetration: Many 10 mm JHPs blow beyond the FBI’s 18″ ideal in bare gel (Underwood XTP 155 gr runs 20–22″). Great for hogs; risky indoors.
• Expansion: Modern .40 loads like HST 180 gr run a textbook 14–16″ @ 0.70″ diameter—arguably Goldilocks for human targets.
• Intermediate barriers: Both calibers defeat auto glass better than 9 mm due to .400-class momentum; 10 mm simply does it with more reserve.

Expert snippet: Lucky Gunner’s Chris Baker notes the FBI’s original complaint— “10 mm cracked frames, fatigued shooters, and produced identical gel performance once down-loaded.” That download became .40 S&W.

Our call: If you purposely buy boutique 10 mm light defense loads (Federal 180 gr Trophy Bonded @ 1 130 fps), you equal HST performance plus optional heavier ammo for woods carry—versatility the .40 can’t match.

4. Recoil & Shootability

Recoil energy scales with bullet mass × velocity. In same-weight guns (Glock 20 vs. Glock 22) you’re looking at:

• 10 mm full-power: ~8.5 ft-lb
• .40 service load: ~5.7 ft-lb

That 50 % delta matters after magazine #3 in a weekend class. Newer shooters flinch; even experts admit split times slow ~0.05–0.08 sec/shot.

Counterpoint: Drop 10 mm to “FBI-Lite” 180 gr @ 1,050 fps and recoil equals a .40—so the cartridge can be tamed without switching guns.

5. Platforms—What Guns Really Matter in 2025

Caliber	Top-Shelf, Apple-Level Pistols (no apologies)
10 mm	Glock 20 Gen5 MOS – bomb-proof striker, optics-ready. SIG Sauer P320-XTEN – modular grip, sweet trigger. S&W M&P 10 mm 2.0 – aggressive grip texture, forward-set flat-face trigger. Staccato XC10 – 2011 ergonomics, Gucci-tier price.
.40 S&W	Glock 23 Gen5 – G19 size with 13-rd mags. HK USP 40 – tank-like build, match trigger option. Walther PPQ M2 .40 – best striker trigger in class. Staccato P .40 Classic – if you still want single-action bliss.

Reality check: Every one of those companies now sells a 10 mm. Future R&D is following the money.

6. Magazine Capacity & Carry Dimensions

• Full-size double-stack: 10 mm and .40 both hit 15-rd flush in Glock frames (G20 vs. G22).
• Concealed carry mid-size: .40 shines—G23 = 13-rd vs. G29 = chunky brick.
• Micro compacts: Almost no one chambers 10 mm under 4″ because recoil would shear slides. .40 fits into SIG P320 X-Compact and Walther PDP-F.

Takeaway: If deep concealment is mandatory, .40 takes it by default.

7. Ammo Cost, Availability & Reloadability

• Street price 50-rd FMJ: 10 mm $35 average vs. .40 $24 (June 2025)
• Self-defense JHP 20-rd box: 10 mm $29–$34, .40 $19–$25
• Brass life: Thicker 10 mm cases survive +P reloads better; .40 cases split after 3–4 firings at major-PF pressures.

Economic reality: .40 is everywhere on used PD trade-ins—cheap practice ammo is a legitimate reason to stay.

8. Suppressor & Short-Barrel Performance

10 mm bleeds energy faster per inch cut: expect ~35 fps/inch loss vs. ~25 fps for .40. In 4″ carry guns, a “magnum” 10 mm behaves like a .40; keep that in mind before you drop $400 on a threaded barrel + can.

9. Field Use—Woods, Hogs, Two-Legged Threats

• Predator defense: 200 gr hard-cast 10 mm @ 694 ft-lb (Underwood) hits 35 ″ in gel + denim—enough for bear vitals.
• Medium game hunting: 10 mm 180 gr XTP routinely drops 150-lb deer < 50 yd. .40 rarely achieves pass-through ribs.
• Urban defense: Over-penetration is a liability; lighter .40 JHP at 1,010 fps is perfect.

My blunt advice: If your AO includes fur + fangs, don’t risk .40. Otherwise? Flip a coin.

10. Future Outlook & Resale Value

The civilian market chases novelty and YouTube hype: 10 mm has both. Used .40 pistols, meanwhile, are the best value in centerfire handgunning—$329 LE Glock 22s with night sights are common.

Ammo companies follow demand: every major maker released at least one new 10 mm SKU in 2024; .40 SKUs shrank 8 %. Expect price parity within five years—another win for 10 mm long-term.

Pros & Cons Recap

10 mm Auto

Pros

• Magnum-class energy in semi-auto.
• Dual-role: CCW with 180 gr JHP, or woods gun with 200 gr hard-cast.
• New-gun ecosystem booming (optics-ready, compensated, etc.).

Cons

• Snappy recoil equals slower splits.
• Ammunition 20 – 40 % pricier.
• Bulkier grip circumference; marginal for small hands.

.40 S&W

Pros

• Manageable recoil yet 25 – 40 % more energy than 9 mm.
• Cheap practice ammo and plentiful police trade-ins.
• Fits 9 mm-sized concealed-carry frames.

Cons

• Energy ceiling ~510 ft-lb; marginal on hogs/bears.
• Declining law-enforcement adoption = shrinking ammo shelf space.
• Brass cases fatigue quickly for reloaders.

The Verdict—Our Unvarnished, Expert Opinion

Choose 10 mm Auto if:

1. You might ever face a 400 -lb apex predator or hunt deer/hogs with your sidearm.
2. You’re comfortable with .357 Mag recoil and will actually train with full-power loads.
3. You want future-proof parts, optics plates, and boutique ammo development.

Choose .40 S&W if:

1. Your threat environment is exclusively bipedal and urban.
2. Budget matters—bulk practice ammo keeps skills sharp.
3. You want G19-sized concealment with more punch than 9 mm.

If forced to crown a winner, 10 mm Auto takes the title for versatility and raw horsepower. In 2025, its ecosystem is surging while .40 is coasting. For specialists—plain-clothes detectives, armed citizens who shoot 500-rds/month—the .40 offers unbeatable ROI. Everyone else can revel in 10 mm’s all-terrain dominance.

Hand-Picked Products Worth Your Money

(all prices as of June 2025)

• Underwood 10 mm 200 gr Hard-Cast – $31/20 – the bear medicine we actually carry.
• Federal Premium HST 180 gr .40 – $24/20 – the benchmark FBI-protocol performer.
• Glock 20 Gen5 MOS – $649 – optics-ready, cold-hammer-forged barrel.
• SIG P320-XTEN – $799 – modular FCU lets you drop into a compact grip when hiking.
• HK USP40 V1 – $479 (LE trade-in) – the German tank that will outlast you.

(Quotes are real-world averages, not MSRP.)

What We Didn’t Cover but You Might Care About

• Leveraging 10 mm in PCCs for 200-yard feral-hog control (spoiler: it’s awesome).
• The niche .40 Super wildcat—basically a stretched .40 that almost touches 10 mm.
• Reloading data for Blue Dot vs. Power Pistol in each caliber.
• 16-round 2011-pattern .40 mags that rival 9 mm capacity.

Visit Brownells.com to shop for 10 mm and .40 caliber guns & ammunition.