Benelli - Inertia Driven® System

“The Law of Inertia” is Newton’s First Law of Physics and is as consistent and unchangeable as The Law of Gravity. Benelli has harnessed this basic law of physics in the Inertia Driven® system to operate the world’s fastest, simplest and most reliable semi-automatic shotguns. It’s not boasting, it’s the law — “The Law of Inertia.”

Inertia Driven® is the Best Operating System Ever Devised — Period!

Simple — Inertia Driven® is simple with only three primary parts: the bolt body, the inertia spring and the rotating bolt head. Simple is better.
Faster — With a greatly reduced mass of parts, Inertia Driven® is faster.
Cleaner — Gas, smoke and burnt powder stay in the barrel where they belong, rather than being channeled into the gun’s mechanism, as they are in gas systems.
Strong — The massive steel locking lugs on the Inertia Driven® system’s rotating bolt head not only lock steel-to-steel into the gun’s barrel; the lugs are locked-in tighter during firing.
Low Maintenance — The Inertia Driven® system is much cleaner so gun cleanup takes a fraction of the time that it takes to clean a gas system gun.
Light Weight — The Inertia Driven® system is not only incredibly simple; it is also lightweight, allowing Benelli shotguns to be some of the lightest semi-automatic shotguns ever produced.
Perfect Balance — With no springs, action bar linkage or heavy gas cylinder under the fore-end, Benelli’s Inertia Driven® shotguns balance like a fine game gun should.
Reliable — The Inertia Driven® system never needs adjusting and will cycle anything from field loads to 3½˝ magnums with consistent reliability, year, after year, after year. In fact, there are Inertia Driven® Benelli shotguns that have fired over 350,000 rounds, still in the field and functioning perfectly.

Benelli's Intertia Driven™ System - Cycle of Operation

Step One: Chambering

As the bolt assembly moves into battery, the locking head pin moves along a curved track in the bolt body to rotate the steel bolt head into engagement with the steel barrel extension. The cartridge drop lever is down, its red dot indicating that the gun is cocked.

Cartridge drop lever (Works three ways:)

Pulling back on the operating bolt handle and pressing the cartridge drop lever locks the bolt to the rear.
With bolt forward, pressing it releases a shell onto the carrier.
Visibility of the red dot indicates the hammer is cocked.

Step Two: Firing

When the trigger is pulled, every part of the shotgun except the bolt body moves rearward. The curved track in the bolt body, which is moving forward relative to the rest of the gun, presses against the locking head pin, turning the bolt head even tighter into the barrel extension. At the same time, the inertia spring is compressed between bolt head and body. The cartridge drop lever moves up, allowing a shell to move from the magazine to the carrier.

Step Three: Recoil

Near the end of the recoil cycle, chamber pressure drops to a safe level and the gun’s rearward motion slows. The heavy inertia spring then thrusts the bolt assembly rearward, unlocking the rotating bolt head, extracting the spent shell from the chamber and pulling it against the ejector.

Step Four: Ejection

As the empty shell exits the receiver, the energy of the moving bolt assembly recocks the hammer and compresses the recoil spring in the buttstock. The recoil spring then thrusts the bolt assembly forward, lifting the oncoming shell into position and chambering a fresh cartridge. The gun is ready to fire again in a fraction of a second!