Best Ammo for Semi-Auto Shotguns: What Actually Cycles

Why some shells won't cycle

A pump or break-action shotgun does not care how hard a shell kicks. You supply the energy to cycle it. A semi-auto takes that energy from the shot itself, and if the shell does not provide enough, the bolt does not travel far enough to eject the empty and pick up the next round. You get a failure to eject, a stovepipe, or a bolt that closes on an empty chamber.

Autoloaders use two main systems:

• Inertia-driven. Benelli's best-known design. The gun recoils, a spring inside the bolt stores energy and the bolt unlocks and cycles. Benelli describes the system as clean, reliable and adjustment-free. Because it runs on recoil, it needs enough recoil.
• Gas-operated. Beretta, Mossberg and many others bleed a little gas from the barrel to drive a piston. Gas systems are generally more forgiving of light loads and soften felt recoil, but they get dirty faster and still have a lower limit.

Either way, the maker sets a minimum. Find it in your owner's manual or on the product page.

Dram equivalent and velocity, decoded

Shotshell boxes still print a number in "drams." A dram is 1/16 of an ounce, about 27.3 grains. In the black powder era, a 3 or 3-1/2 dram charge was a common hunting load, and the number told you how much powder was inside.

Modern shells use smokeless powder, so "3 dram equivalent" now means a load that matches the velocity of the old 3-dram black powder load with the same shot weight. In practice it works as a velocity rating. Many boxes print the velocity in feet per second as well, which is easier to compare.

For cycling, two numbers matter together: payload (ounces of shot) and velocity. More of either means more recoil, and more recoil means more energy to run the action. That is why a 1-1/8 oz load cycles guns that a 7/8 oz load will not.

The break-in factor

A common report from semi-auto owners is that a new gun runs light loads poorly at first and better after a few boxes of heavier shells. Check whether your owner's manual says anything about break-in. Either way, it costs little to run a box or two of full-power field loads through a new gun before you judge it on light target shells.

Other causes of cycling trouble that have nothing to do with the shells: a dirty or dry action, the wrong lubricant, a loose magazine cap on some designs, a gas system assembled incorrectly after cleaning, and a shooter who holds the gun too loosely. With inertia guns in particular, a soft shoulder mount can soak up the recoil the gun needs.

Best target and practice loads

What about 1 oz and 7/8 oz loads?

Light loads like Winchester Super-Target 1 oz #8 and 7/8 oz "featherlite" target loads are pleasant to shoot and run well in many gas guns. Buy a box and test it in your gun before you buy them by the case. If you get even occasional failures, step back up to 1-1/8 oz.

Best buckshot and slugs for autoloaders

Full-power buckshot and slugs have more than enough recoil to cycle any semi-auto. The bigger question is accuracy and pattern, which depends on your barrel and choke.

Shell length and the gun you own

Autoloaders commonly accept 2-3/4 and 3 inch shells, and some accept 3-1/2 inch. Ammunition Depot's semi-auto shotgun section lists models such as the Beretta A400 with a 3-inch chamber and the Mossberg 940 Pro Field. Always confirm chamber length on the barrel. A gun chambered for 3 inch shells will fire 2-3/4 inch shells; the reverse is never safe.

A simple test plan

1. Read the manual. Note the minimum load and any break-in advice.
2. Clean and lightly lubricate the action as the maker recommends.
3. Run a box of full-power field loads to confirm the gun is healthy.
4. Test your target load with a firm shoulder mount. Load two, then three shells, to check feeding from the magazine.
5. Buy in bulk only after a clean box or two. For defensive loads, test from every position you might use.

Editorial note: This is an independent editorial overview built from manufacturer specifications, retailer listings and published sources. We have not performed hands-on testing of the products discussed, and nothing here is a performance guarantee. Verify specifications, compatibility and the law where you live.

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