Ammo for Glocks: range, carry, +P and unsupported chambers

A Glock eats almost anything, which makes ammunition choice easy at the range and easy to get wrong for carry. The questions we get most are the same ones: which weight, which brand for carry, whether +P is safe, whether steel cases hurt the gun, whether lead bullets are allowed, and what the old warning about unsupported chambers means. This guide answers each for 9mm first, then notes the other calibers.

Practice ammunition

Full metal jacket 9mm in 115, 124 or 147 grain from any major maker. It is the cheapest centerfire pistol round there is, it feeds in every Glock, and the weight matters little for practice; 124 grain is closest to most defensive loads in recoil and point of impact. Buy by the case for the range and shoot it. Remanufactured ammunition from a reputable loader is fine for practice; Glock's manual excludes damage from reloads under the warranty, which is a reason to use factory ammunition in a carry gun and a caution for the range.

Defensive ammunition

A jacketed hollow point with a service record. The loads police agencies issue have been tested through barriers and clothing and expand reliably from a 4 inch barrel: the bonded 124 grain +P loads, the 147 grain standard-pressure loads and the 135 grain +P loads from the large ammunition companies are the usual choices. Pick one, shoot at least a box of it through your pistol to confirm it feeds, load the magazines, and replace it yearly. For a subcompact or slimline with a barrel under 3.5 inches, choose a load the maker tests from short barrels; some 147 grain loads expand poorly at the lower velocity.

+P and +P+

+P is a standard pressure increase of about ten percent set by the industry body, and every Glock is rated for it; it adds recoil and wear, so shoot it enough to be familiar and practice with standard pressure. +P+ has no standard and can be loaded well beyond +P; Glock does not recommend it and neither do we. 9mm NATO is loaded near +P and is fine.

Bullet weight

115 grain is fastest and snappiest, 124 grain the middle and the most common defensive weight, 147 grain the heaviest, slowest and softest-recoiling and subsonic for suppressed pistols. Point of impact shifts a little between them; zero your sights with the weight you carry. None is wrong.

Steel and aluminum cases

Steel-cased 9mm runs in a Glock. It is dirtier, the steel case does not seal the chamber as well as brass so more residue blows back, and the extractor works harder; over thousands of rounds it wears the extractor faster. Aluminum cases are fine and clean. Neither hurts the barrel. For a carry gun, brass; for the range, whatever is cheapest that runs.

Lead bullets and polygonal rifling

Factory Glock barrels through Gen 4 use polygonal rifling, which has no sharp grooves to scrape lead off a bullet, so lead builds up in the bore faster than in a conventional barrel and, if ignored, raises pressure. Glock's manual says not to use bare lead bullets. Jacketed, plated and polymer-coated bullets are fine. Shooters who cast or shoot coated lead usually fit a conventionally rifled aftermarket barrel, or run the Gen 5 Marksman Barrel, which is conventionally rifled. If you do shoot lead in a polygonal barrel, clean it every hundred rounds and inspect for buildup.

The unsupported chamber

Early Glock .40 S&W pistols had chambers that left more of the case head exposed at the feed ramp than some other designs, and hot reloads in those chambers bulged cases, which became a well-known warning. Current 9mm and .40 Glocks have more support, and factory ammunition within pressure limits is not a problem in any of them. The warning survives as advice: do not shoot hot reloads in a Glock, particularly in .40, and do not reload cases that show a bulge at the base.

The other calibers

.40 S&W: 165 or 180 grain, hollow points from the same makers; a sharper recoil. 10mm: read the box, because much commercial 10mm is loaded down to .40 levels, and full-power loads from the makers who state velocity are what the cartridge is for; hard-cast or bonded bullets for hunting and bears. .45 ACP: 230 grain standard, hollow points for defense, subsonic by default. .380 for the 42 and 25: choose a load tested from short barrels. .22 LR for the 44: high-velocity rounds, since the pistol is picky with standard velocity.

Testing a load in your pistol

Every Glock feeds almost everything, but the word is almost. Before a load goes into a carry magazine, shoot 50 to 100 rounds of it through the pistol, from every magazine you carry, and note any failure to feed, extract or lock back. Check the point of impact against your sights at 10 and 25 yards. A load that runs clean through that test in your pistol is your carry load; a load that stumbles once is a range load until it proves otherwise.

Storage and rotation

Store ammunition cool, dry and sealed; it lasts decades. Shoot carry ammunition yearly and replace it. Do not chamber the same round repeatedly; setback into the case raises pressure, so shoot the chambered round at the next range trip. Keep range ammunition and carry ammunition in different boxes.

Your state's rules on ammunition shipping are on our city pages. Keep the barrel clean with the maintenance schedule, and carry the pistol in a holster from the holster guide. Browse 9mm and other ammunition; it ships with an adult signature where legal.

General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.