What Every Benelli M4 Owner Should Know From the Manual

The Benelli M4 manual runs 138 pages in six languages. This is the English content boiled down: every procedure, spec and warning that matters, in the same order you'd use them, without the repetition. Based on the 2011 international edition; some details (stock type, magazine capacity) vary by model and market.

How the M4 actually works

The M4 is a semi-auto 12 gauge fed from a tube magazine. It runs on Benelli's ARGO Twin system: Auto-Regulating Gas Operated, with two gas ports, two cylinders and two pistons sitting just ahead of the chamber. The bolt has a rotating head with two locking lugs.

The manual breaks every shot into eight steps:

1. Firing: the hammer hits the firing pin and the shell fires. Some of the gas pushing the shot down the barrel is tapped off into the two cylinders.
2. Unlocking: the pistons drive the bolt back and the bolt head rotates open.
3. Extraction: the empty hull is pulled out of the chamber.
4. Ejection: the hull is thrown clear of the gun.
5. Cocking: the hammer is reset for the next shot.
6. Feeding: a fresh shell comes out of the magazine toward the chamber.
7. Chambering: the shell goes into the chamber.
8. Locking: the bolt head rotates closed and seals the chamber.

The cartridge drop lever and the red dot

The one control that confuses new owners most is the cartridge drop lever, the small lever sticking out under the receiver in front of the trigger guard. Here's what the manual says it does: when the hammer is cocked, the lever lets the carrier latch release one shell from the magazine onto the carrier. That shell then pushes the latch back so a second shell stays in the tube.

The tip of the lever has a red dot. If you can see the red dot, the hammer is cocked. If you can't, it isn't. Keep that in mind, because it's the key to loading the gun (next section).

Assembling a new gun from the box

The box holds four pieces: the stock-receiver-bolt unit, the barrel, the two fore-end halves, and the cocking lever (charging handle).

1. Push the cocking lever fully into the bolt.
2. Unscrew the fore-end cap from the magazine tube.
3. Holding the receiver, use the cocking lever to pull the bolt back until it locks open. The safety should be set to fire for this step. If the bolt won't stay open, press the cartridge drop lever and try again.
4. Remove the plastic sheath from the barrel.
5. With the bolt locked open, slide the barrel over the magazine tube toward the receiver. Make sure the tube goes through the barrel guide ring.
6. Fit the two fore-end halves together and seat them in the retaining band at the rear of the barrel.
7. Slide the barrel into the receiver, with the barrel extension resting on the bolt head, until it clicks into place. Don't let the barrel extension hit the bolt locking head on the way in.
8. Screw the fore-end cap back on and tighten it firmly, so the barrel and fore-end are locked tight against the receiver. None of the chrome barrel extension should be visible at the front of the receiver.
9. Press the carrier button to close the bolt.

Loading, unloading and swapping rounds

The safety

The safety is the crossbolt button in the trigger guard. When you can see the red ring, the gun is ready to fire. Push it until the red ring disappears and the gun is on safe.

Why your loading gate "locks"

This is the number one question we get. The manual is clear: the gun has to be loaded with the hammer cocked, or the carrier latch can't hold the shells in the tube as you push them in.

The manual's loading steps:

1. Put the safety on, point the gun in a safe direction, and open the bolt to confirm the gun is empty. Close it again.
2. Check for the red dot on the cartridge drop lever. If it isn't showing, press the carrier button, pull the bolt back by hand, and let it close. The red dot should now be visible.
3. Turn the gun over and push shells into the magazine one at a time until the carrier latch catches each one.

If the hammer isn't cocked, shells won't stay put and it feels like the gate is jammed. Cock the hammer and it works.

Getting a round in the chamber

With a loaded tube, the gun still won't fire until there's a shell in the chamber. The manual gives two ways:

• Direct: open the bolt, drop a shell into the chamber through the ejection port, and release the charging handle. Your tube stays full.
• Indirect: hold the bolt open, press the cartridge drop lever so the first shell drops onto the carrier, then release the charging handle. This takes a round out of the tube, so top it off with one more shell afterward.

Swapping the round in the chamber

Want to switch from buckshot to a slug? With the safety on and the muzzle pointed somewhere safe, open the bolt to eject the chambered round. Then either drop a new shell in through the ejection port and let the bolt close, or press the cartridge drop lever and let the bolt close to feed the next shell from the tube.

Unloading

With the safety on and the muzzle pointed somewhere safe:

1. Open the bolt to eject the chambered round.
2. Ease the bolt closed with the charging handle.
3. Turn the gun over, push the carrier in, and press the front of the carrier latch with your index finger. One shell comes out. Repeat for each shell.

You can also unload by repeatedly using the cartridge drop lever and cycling the bolt.

What ammo the M4 takes

The manual keeps this short:

• 12 gauge, 2 3/4" (70 mm) or 3" (76 mm) shells. You can mix them, and the gun needs no adjustment to fire either length. That's the "auto-regulating" part of ARGO.
• Never use a shell longer than the chamber. The manual warns of serious consequences for the gun and the shooter.
• New, factory-loaded ammo only. The safety section warns against reloads, which can cause excessive pressure or case-head ruptures.
• Every Benelli shotgun is proof-tested at the Italian National Proof House in Gardone Val Trompia at 1,370 bar.

Shell Tactical note: the manual gives no minimum load. Some very light loads won't cycle reliably, so test your defensive load in your own gun.

Field stripping, cleaning and lubrication

No tools needed

The manual points out that the M4 is modular and needs no armorer's tools to strip. The charging handle doubles as the tool: you use its tip to push out the trigger guard pin and to unscrew the gas cylinder plugs.

The full strip, in short: pull the bolt back, press the cartridge drop lever, unscrew the fore-end cap, slide the barrel and forearms off, ease the bolt forward, pull out the charging handle and bolt, take the bolt apart (firing pin, locking head pin, locking head), push out the trigger guard pin and remove the trigger group, take off the stock and pistol grip, then unscrew the gas plugs and slide the pistons out the front.

Do NOT oil the gas pistons

If you remember one thing from the manual, make it this. Benelli repeats the same line five times in the maintenance section: the inside of the cylinders and the gas pistons do not require lubricating.

Oil in the gas system bakes into carbon, makes the gun smoke, and gives dirt something to stick to. Clean the pistons and cylinders and leave them dry.

What to clean, and how often

• Before first use: clean the gun after taking it out of the box. It ships coated in protective oil.
• After every use: clean and lube the barrel, the trigger group (hammer, trigger, etc.) and the bolt. Take out the gas plugs and clean the pistons. How often the pistons need it depends on the ammo you shoot.
• At least every 250 rounds, and at the end of every range session, clear out dirt and dust.

Use a CLP-type oil (Cleaning, Lubricant, Protective) in a thin, even coat on metal surfaces. Benelli's own oil and cleaning kit comes with the gun.

What not to clean it with

The manual rules out water-based cleaners, anything abrasive, alkaline or acidic, abrasive powders, steel wool and metal brushes. Use gun-specific solvent, a soft cloth or chamois, and a sponge with no metal in it.

Storage

Out of the box, store the gun somewhere dry, closed and ventilated, and check at least once a month that all metal parts still have a coat of CLP. A gun still sealed in its original packaging should be checked at least every six months.

Reassembly mistakes to avoid

• Locking head pin: the reference line on top of the pin has to be visible and lined up with the length of the bolt.
• Firing pin spring: always make sure it's installed.
• Firing pin: insert it with your fingers only, never with a tool.
• The link: once the bolt is in, check that the link slides over the trigger group and onto the recoil spring plunger inside the receiver.
• Pistol grip: screw it on until it seats against the receiver, then turn it no more than one extra turn to line it up.

The troubleshooting section, in full

The manual's troubleshooting page is short. If the gun won't fire, check that the safety is off, that there's a shell in the chamber, and that the firing mechanism is clean and lubed.

The other item is worth repeating: especially after the first few rounds, check that the magazine cap is tight. It's what holds the barrel against the receiver. When the barrel is seated properly, none of the chrome barrel extension should be visible at the front of the receiver.

Stock, sights, chokes and magazine

The telescoping stock

The edition we read covers a two-position telescoping stock (short and extended). To shorten it: press the locking button, rotate the stock clockwise (looking from behind), push it forward to the stop, rotate it back counterclockwise and let go of the button. Reverse the steps to extend it.

To take the stock off completely, rotate it the same way but push it forward to the line marked on the recoil tube, rotate it back, and pull it off the rear of the tube.

Shell Tactical note: the stock only adjusts if your recoil tube has notches for it, and many factory tubes have fewer positions or none. Shell Tactical 6-position recoil tube

Adjusting the rear sight

Use a coin or the rim of a shell.

• Windage (screw on the right side of the rear sight): counterclockwise moves your point of impact left, clockwise moves it right.
• Elevation (screw on top of the elevating platform): counterclockwise raises point of impact, clockwise lowers it. You can count the clicks or read the scale on the back of the platform.

Choke tubes

If your M4 came with internal chokes, the manual has a few firm rules:

• Never fire without a choke installed in a barrel threaded for one.
• A correctly installed choke must not stick out past the muzzle. Use only Benelli chokes of the right length for your barrel.
• Take the choke wrench out of the muzzle before you shoot. The manual says this twice.
• If the threads are dirty, clean them by spinning the threaded end of the wrench in the barrel. Clean the choke and threads before putting the gun away.
• Start the unthreaded end of the choke into the barrel first, then thread it in and tighten it firmly with the wrench.

Benelli chokes are marked with notches so you can tell them apart even when installed: one notch is Full, two Improved Modified, three Modified, four Improved Cylinder, and five Skeet.

Magazine capacity and the spring warning

The manual says the magazine holds six shells of either length, and that capacity should be cut with a limiter where the law requires it. That figure doesn't match US civilian guns: Benelli lists standard M4 Tactical models at 5+1, and some models ship with a 7+1 tube. 3" shells are longer, so the same tube holds fewer of them than 2 3/4" shells.

Anyone pulling the magazine cap (to install a limiter, swap a tube, or add an extension) should heed this warning: the magazine spring is under tension and can fly out at high speed. Hold it by hand as you take the cap off, and wear eye protection.

The warranty fine print

Two things in the warranty section are worth knowing:

• Benelli's 5-year corrosion warranty covers corrosion that eats all the way through a part, not surface pitting or cosmetic marks. The part has to be intact (no dents or gouges), the gun has to have been maintained per the manual's maintenance criteria, and it has to be within five years of delivery. If a part qualifies, Benelli replaces it after inspecting it. That's the full extent of the remedy.
• The manual states that non-original Benelli parts void the warranty, and that Benelli isn't responsible for damage from improper ammo, lack of maintenance or misuse.

If you upgrade your M4, hang on to your factory parts. If you ever need warranty service, contact Benelli first and ask how they'll handle your gun.

Quick reference

• Red dot showing on the drop lever = hammer cocked. You need it showing to load the tube.
• Red ring showing on the safety = ready to fire.
• 2 3/4" or 3" 12 gauge, mixed freely, no adjustment. Never longer than the chamber.
• Don't oil the gas pistons or the inside of the cylinders.
• Clean after every session and at least every 250 rounds. CLP on the metal, no metal brushes.
• Check that the magazine cap is tight, especially after the first rounds.
  
• Hold the magazine spring and wear eye protection when you open the magazine.

---

Got an M4 question the manual doesn't answer? Get in touch, or browse our Benelli M4 parts and upgrades. We make most of what we sell, and we're always glad to talk M4s. Benelli Official User Manual