.40 S&W Ammo

What is .40 S&W?

.40 S&W (Smith & Wesson) was designed in 1989-1990 as a deliberate compromise. The FBI had adopted 10mm Auto after the 1986 Miami Shootout — the deadliest day in FBI history, where two agents were killed in a prolonged firefight that exposed the inadequacy of .38 Special revolvers against determined opponents wearing body armor. But 10mm at full power proved too much for many agents to handle, and the Bureau was downloading loads to reduce recoil. Those downloaded loads barely outperformed 9mm, delivered in a much larger frame that a significant portion of agents couldn’t shoot well.

Smith & Wesson and Winchester solved the problem by shortening the 10mm case by 7mm, reducing pressure slightly, and loading it to specs that matched the FBI’s downloaded 10mm loads. The result fit in a standard double-stack 9mm-framed pistol with minimal modification. The .40 S&W was announced in January 1990 and hit production in six months, one of the fastest cartridge-to-market timelines in the industry’s history.

The FBI adopted it immediately. So did most major U.S. law enforcement agencies throughout the 1990s and 2000s. For about 25 years, .40 S&W was the dominant U.S. police cartridge. The Glock 22 and M&P40 were the standard issue pistols for a generation of officers.

The FBI switch and what it actually means

In 2014, the FBI announced it was switching back to 9mm. The reasoning was documented in a detailed technical memo: modern 9mm JHPs performed comparably to .40 S&W in terminal effectiveness under FBI protocol testing. 9mm offered higher capacity, lower recoil (enabling faster accurate follow-up shots), and meaningfully lower cost for training. Agents shot better with 9mm. Better shooting matters more than a marginal energy advantage.

Most agencies followed. .40 S&W stopped appearing in new department RFPs. Glock production of .40 models slowed. The institutional shift was decisive and fast.

What the FBI memo did not say: that .40 S&W is ineffective. The terminal performance argument is about the gap closing, not .40 failing. Modern 180gr HST and Gold Dot loads still pass all six FBI barrier tests. The decision was about shootability and economics, not about .40 S&W being dangerous to use.

That distinction matters if you already own one, shoot one well, or are evaluating a used pistol at a discount.

.40 S&W vs. 9mm: the honest accounting

Terminal performance in FBI-protocol gel testing is genuinely similar between modern JHP loads in 9mm and .40 S&W. The gap isn’t large enough to be a practical consideration at defensive engagement distances. Where .40 loses is in capacity and shootability: two fewer rounds and harder recoil both affect real-world performance more than the marginal energy difference.

.40 still makes sense if you already own one, picked up a used pistol at a discount, or compete in USPSA limited division where major power factor matters. If you’re buying new and selecting a caliber from scratch, the math points to 9mm.

The used gun opportunity

This is the part most caliber comparisons skip. When agencies switched to 9mm, they liquidated hundreds of thousands of .40-caliber service pistols. Glock 22s, M&P40s, Sig P226/P229s hit the used market at $300-450. New, these guns run $500-650.

A police trade-in Glock 22 is not a worn-out gun. Departments fire far fewer rounds per year than most serious hobbyists. Many of these pistols have under 2,000 rounds through them. They went through armorer inspections and were maintained under departmental programs. At $350, the higher cost of .40 S&W ammo doesn’t erase that savings for years of regular shooting.

That math flips if you’re buying new. Then the 9mm argument is straightforward. On the used market right now, the .40 is hard to beat for the money.

Bullet weight: 155gr vs 165gr vs 180gr

The grain weight choice in .40 S&W is less complicated than 9mm because the caliber’s defensive use cases have largely narrowed around two weights.

155 grain runs fastest, typically 1,175-1,205 fps from a 4-inch barrel. It expands aggressively but can sometimes under-penetrate if barriers are involved. Not the first choice for duty or defensive use, but still used in competition for slightly flatter recoil.

165 grain is the middle ground. At 1,130-1,150 fps, it passes FBI barrier tests reliably and has slightly better expansion than 180gr. Federal HST and Winchester PDX1 in 165gr are legitimate defensive options. The tradeoff is slightly less penetration depth than 180gr through heavy clothing.

180 grain is the FBI-standard weight and the most proven load in the caliber. At 950-1,025 fps, it’s slower but penetrates deeper and retains weight better through barriers. Federal HST 180gr and Speer Gold Dot 180gr are what federal law enforcement carried for two decades. Both pass all six FBI protocol tests consistently. If you’re choosing a defensive load and aren’t sure where to start, 180gr HST or Gold Dot is the answer.

Defensive ammo recommendations

The FBI protocol requires 12-18 inches of penetration in 10% ballistic gelatin after passing through six barrier types: bare gel, heavy clothing, drywall, plywood, steel, and auto glass. Expansion must reach at least 1.5x original diameter. These are the loads that pass consistently in .40 S&W.

Federal HST 180gr is the benchmark. The same load issued to federal agents. Skived petals unfold reliably through barriers without clogging on clothing fibers. Penetrates 14-15 inches with 0.76-inch expanded diameter. Available to civilians as Federal Personal Defense HST. This is what to carry if you’re carrying a .40.

Speer Gold Dot 180gr is the other half of the law enforcement market. Electrochemically bonded jacket that resists separation through barriers. Consistent 14-inch penetration, 0.71-inch expansion. The bonded construction is what matters here: jacket and core stay together even after punching through intermediate barriers. Used by dozens of major departments for two decades.

Federal HST 165gr runs about 120 fps faster than the 180gr load and still passes all FBI barrier tests. Penetrates slightly shallower (13.4 inches) with comparable expansion. A legitimate alternative if you want more velocity, though the 180gr is the proven standard.

Winchester PDX1 165gr is a bonded JHP with wide retail distribution. Solid terminal performance, available at most sporting goods stores. Bonded construction prevents jacket separation.

Hornady Critical Defense 165gr FTX uses a polymer tip to prevent clothing clog on hollow point expansion. Widely available, including at Walmart. It doesn’t quite match the penetration depth of HST or Gold Dot through heavy clothing, but it’s a solid option when the premium LE loads are backordered.

Speer Lawman 180gr TMJ is a practice round with a total metal jacket (fully enclosed base), popular at indoor ranges that prohibit exposed lead. Run this for training volume, not carry.

FMJ vs JHP

FMJ is a copper-jacketed lead core with no hollow cavity. It doesn’t expand on impact. Use it for range training and practice. The cost difference between FMJ and JHP is significant enough that running FMJ for all training makes sense, with JHP reserved for carry and defense.

Don’t carry FMJ. It over-penetrates, dumps less energy into the target, and increases the risk of hitting something behind your intended target. Federal law enforcement dropped FMJ for defensive use decades ago for exactly this reason.

JHP expands on impact, transferring energy into the target rather than through it. All premium defensive loads are JHP variants. In .40 S&W, the specific construction (HST, Gold Dot, PDX1) matters as much as the grain weight. A quality bonded 180gr JHP outperforms a generic budget hollow point regardless of what’s printed on the box.

Ballistics data

From a 4-inch barrel:

FBI gel data

FBI protocol (10% gel, 4 denim layers, 4” barrel):

The 180gr HST and Gold Dot perform well across all barriers. Consistent expansion, deep penetration, good weight retention. This is legitimately competitive terminal performance, comparable to the top 9mm loads.

Brand guide

Federal HST 180gr is the LE standard, same load issued to federal agents. Deep penetration, consistent expansion. ~$0.85-1.20/rd.

Speer Gold Dot 180gr is bonded construction with high retained weight. The other half of the law enforcement market. ~$0.85-1.20/rd.

Federal HST 165gr runs slightly higher velocity than 180gr with reliable expansion. ~$0.85-1.20/rd.

Winchester PDX1 165gr is a bonded bullet with wide distribution and solid performance. ~$0.80-1.15/rd.

Hornady Critical Defense 165gr FTX uses a polymer tip for reliable expansion, widely available. ~$0.80-1.15/rd.

Blazer Brass 180gr FMJ is the cheapest reliable practice ammo. ~$0.28-0.40/rd.

Federal American Eagle 180gr FMJ is brass case, cleaner than steel or aluminum, consistent. ~$0.30-0.42/rd.

Speer Lawman 180gr TMJ is a total metal jacket load, fully enclosed base, popular for indoor ranges with strict lead rules. ~$0.35-0.48/rd.

Price guide (2025-2026)

.40 S&W practice ammo costs roughly 25-35% more than equivalent 9mm. At 500 rounds a month for training, that adds up.

Competition (USPSA/IDPA)

Power factor = (bullet weight in grains × velocity in fps) ÷ 1,000. USPSA major power factor requires 165 PF. A 180gr bullet at 920 fps = 165.6 PF. Standard factory .40 S&W loads make major without handloading, without +P, and with comfortable recoil margins.

That’s the primary reason serious limited-division competitors still run .40. Making USPSA major in 9mm requires pushing velocities that add recoil. In .40, you’re making major at moderate pressure with standard factory loads.

The Glock 35 (5.31-inch barrel, 15+1) is the classic limited gun. Longer sight radius, slightly higher velocity, same capacity as the Glock 22. Used Glock 35s are available at the same depressed prices as the rest of the former-duty .40 market.

Common myths

“.40 S&W is dead.” The caliber lost institutional favor. The guns still run fine and the ammo is still available everywhere. Millions of .40-caliber pistols are in service and the defensive loads are identical to what law enforcement carried for 25 years. What changed is what the FBI and most departments carry now, not whether the cartridge works.

“.40 has too much snap to shoot accurately.” Recoil management is a training problem, not a caliber problem. Yes, .40 snaps more than 9mm. Shooters who spend time with it, especially with a heavier full-size pistol like the Glock 22, get comfortable with the recoil profile. The FBI’s switch was partly about agents who couldn’t train enough to manage it well, not about the caliber being unshootable for a prepared user.

“9mm and .40 are basically the same now.” In FBI gel testing with premium JHPs, terminal performance is genuinely similar. That’s accurate. But .40 delivers more energy, carries a heavier bullet, and makes USPSA major without modification. The performance gap closed; it didn’t disappear entirely.

“You can’t find .40 ammo anymore.” You can. It’s not on every shelf in every store, but it’s available at major retailers and online. Prices are higher than 9mm, but supply exists.

Firearms chambered in .40 S&W

• Glock 22 (full-size, 15+1), Glock 23 (compact, 13+1), Glock 27 (subcompact, 9+1), Glock 35 (competition long slide) — the most common .40 platforms; excellent used market availability
• Smith & Wesson M&P40, M&P40 2.0 — ergonomic, widely used by law enforcement
• Sig Sauer P226, P229 — DA/SA, excellent build quality, popular with federal agencies
• HK USP .40, P2000 — German manufacturing, DA/SA
• Springfield XD/XDM .40 — higher capacity than many, grip safety
• Walther PPQ M2 .40 — excellent trigger for the platform
• Beretta 96 series — .40-caliber version of the 92 series, 12+1
• CZ 75 .40 — less common but excellent ergonomics

The Glock 22 and M&P40 dominate the used market. These were ex-police guns, maintained under armorer programs, available at significant discounts.

State purchase restrictions

California, New York, New Jersey, Illinois, Massachusetts, and Connecticut require permits, background checks, or other verification to purchase ammunition online. SendRounds filters retailers by shipping eligibility based on your location.