The Benelli M4 semi-auto 12-gauge is considered by many serious users to be the Cadillac of tactical shotguns, and it happens to be the current general-issue combat shotgun (M1014) of the United States Marine Corps. There are reasons for both, and where price is not a barrier, performance becomes the issue. Benelli has built its name on high quality shotguns that, though they cost more, deliver on demand, and when those demands are high, the guns come through.
A gas-operated platform with dual stainless steel self-cleaning short-travel pistons bearing directly on the bolt assembly, Benelli’s ARGO (Auto-Regulating Gas-Operated) mechanism eliminates the more complicated linkages and heavier parts that other semi-auto designs use, to produce a relatively simple and robust action capable of handling stiff loads all day long.
The M4 comes in several configurations, including variations with standard, skeletonized collapsible, and pistol-gripped stocks. The newest version covered here is the Desert Camo model with an 18.5-inch cylinder bored barrel, 3-inch chamber, fully adjustable LPA ghost ring two-dot rear sight, white dot front blade inside protective ears on an elevated base, 5.25-inch Picatinny optic rail, 4-round tube magazine, pistol-grip buttstock with solid rubber pad, an under-barrel sling point at the front of the handguard and one on each side of the stock, smooth-faced rounded trigger and a crossbolt safety behind the triggerguard.
The M4 uses an alloy frame to keep weight down to 7.8 pounds unloaded, and the three-color Desert Camouflage pattern covers everything but the front sight, 2 inches of black magazine tube, optic rail, rear sight, pistolgrip, triggerguard, sling points, and buttpad. This Benelli looks very businesslike, even if you don’t plan to haul it off to the dunes.
How It Works
The M4 has its own personality, and if you grew up on a Remington 870 pump like I did. The gun appears fairly normal in outline, but it incorporates a thing called a cartridge drop lever, and therein lies the key to this shotgun’s character. The drop lever sticks out the bottom of the frame on the right side just forward of the triggerguard, and knowing what it means when you can and can’t see it is important.
First off, to load the M4 for use, there are two methods of chambering a round. Sounds normal, but hang on: Either method requires the gun be cocked. Starting from an empty gun in uncocked condition, to “combat load” directly into the chamber through its right side ejection port, the bolt is racked to the rear where it locks on its own. Drop a shell in and hit the bolt release button just below the ejection port. Or, to chamber the first round from the magazine tube, the bolt has to be initially cycled to cock the action before the tube can be loaded.
When uncocked, the shell lifter is locked in place and blocks the bottom loading port. Once cocked, the bolt must be fully forward to unlock the shell lifter for magazine tube loading. With a cocked action on a closed bolt, the drop lever displays its red dot (serving as a cocking indicator), and the shell lifter can be swiveled up out of the way with each shell to load the magazine.
Once the magazine is loaded, getting a round into the empty chamber requires you to first depress the cartridge drop lever to allow the magazine to release the first shell. If you don’t, you can cycle the bolt till the moon comes out and the chamber will stay empty. An alternative is pulling the trigger (chamber still empty) once the magazine is loaded, you can then run the bolt to chamber the first shell without using the drop lever.
The M4 can be checked for cocked status either visually or by feel by noting the drop lever and the shell lifter. If the lever is out far enough to see or touch and the lifter is locked, then the gun is cocked.
Once you’ve got a hot chamber, the magazine can be topped off indefinitely as the M4’s fired, as long as the bolt’s forward and it hasn’t locked open on running dry. If it has run dry and locked open, you’ll need to repeat the steps above. The bolt can be manually locked open only on an empty gun, either by retracting it in first, cocking it after the trigger’s been pulled, or by depressing the cartridge drop lever before retracting it. The bolt will automatically lock open on the last round fired from the magazine, but can’t be locked open as long as there’s a shell in the tube.
Removing an unfired round from the chamber is done by cycling the bolt to the rear, preferably with the safety on. If there’s no follow-up shell in the magazine, pushing the drop lever before cycling will lock the bolt to the rear; otherwise it’ll run forward again. The magazine unloads three ways: You can shoot the gun dry, you can hand cycle each shell through the action and out the ejection port by running the bolt manually, and you can release each shell manually through the loading port by depressing the shell retaining lever at the rear of the magazine tube inside the action and sliding the round out.
If you choose to unload by cycling the action manually, you’ll need to push the drop lever each time to release a shell from the magazine. Sounds complicated? Well there’s a bit more to it than a basic pumpgun, but once you learn the combination to run the Benelli, it’s not that bad.
The factory white dot sights are very visible and the shotgun shoulders on target quickly. Since the M4 comes with a short rail for optics, it seemed natural to mount an appropriately named Aimpoint CompM4s on it. I normally prefer magnification in optics, but on a tactical shotgun used anywhere from 5 feet to 50 yards, the red dots are superior for quick acquisition without blur-out on close-in applications and allow a wider field of vision in use with both eyes open.
The 11.8-ounce night vision compatible CompM4s is a rugged unit that attaches quickly without tools on any Picatinny rail, can be removed just as quickly to go to backup/primary sights if needed, offers 16 brightness levels, incorporates a honeycomb KillFLASH anti-reflection front cap, features a 2 minute-of-angle (MOA) dot, can submerge to 150 feet, operates from –50 to +160 Fahrenheit, and runs for up to eight years of continuous use on one AA-size battery (or other alkaline/lithium power source). Eye relief is flexible; I found a full field of view with my eyes with the Aimpoint CompM4s at the forward end of the shotgun’s rail.
The Aimpoint held steady on the rail without any need to re-tighten the mounting knob. The unit comes in complete form with a KillFLASH disc, an Allen wrench, one removable height spacer to adapt to different stocks and users, and two different length hex-headed screws for attaching the spacer bar to the bottom of the CompM4s unit.
The “s” designator, incidentally, identifies the CompM4 with battery compartment at the 5 o’clock position; the CompM4 without an “s” has a 2 o’clock battery position. Why? User preference, allowing accessibility options for gloves and lefties.
Bright sunlight always affects a red dot sight to at least some degree, being able to crank that dot way up was an absolute necessity at the outset under a sunny sky. A wide range of dot settings covers almost any lighting condition you’re likely to use the Aimpoint in, with or without supplemental magnifiers and NVDs (night vision devices). As clouds drifted in during the afternoon, the dot was more effective, and in low-light conditions it beats any irons in speed, even tritiums.
The KillFLASH honeycomb does reduce light travel through the optics and I prefer to use the sight without it, but specific needs may dictate otherwise. Currently in use by four branches of our military services, Aimpoint says the CompM4 is the finest red dot system they’ve ever produced, and I wouldn’t argue it.
The M4 gas system does require a certain level of pressure to operate the action. The “auto-regulating gas-operated” label refers to the fact that it’s not necessary to swap pistons between lighter and heavier shotshell loads, as some other makes of semi-auto shotguns do. The upside is that the dual-piston arrangement safely handles all factory standard and high-pressure magnum loads in 2-3/4- and 3-inch shells without risking damage to the gun.
The downside is the M4 may not cycle some low recoil buck or slug loads commonly used by law enforcement. There’s no set rule for what works and what doesn’t, in terms of a clear line between high and low brass loads, and as always it’s best to test a load in your own sample.
The action is built to run with all full-powered 12 gauge ammunition carried in Marine Corps supply channels, not the reduced loads that many police agencies and civilian shooters use to tame normal 12 gauge recoil levels.
While my test sample would not cycle high-brass Winchester Ranger low recoil buckshot and a low-brass Winchester light birdshot target load, it did run a Federal high velocity low-brass game load without a bobble, as well as low-brass Winchester Ranger low-recoil slugs.
The M4 may not run well with reduced recoil loads, but that’s no loss, since the gas action and sturdy recoil pad make this shotgun quite easy to stand behind. Standard velocity buckshot is surprisingly light on the shoulder, and even heavy 3-inch slugs are quite bearable for most shooters. There’s no great reason to use anything other than full-bore buck and ball to lower recoil; the Benelli does it for you.
Beginning with slugs, the CompM4s was sighted in to print an inch high at 25 yards as a starter setting. Firing off a sandbag for accuracy at 50 yards, the Benelli preferred Winchester’s 1-1/8-ounce Rack Master high velocity slug with a best sub-2-inch 3-shot group, followed by Winchester’s low recoil Ranger slug at a hair under 4 inches.
The 3-inch 7/8-ounce Partition Gold sabot tends to periodically keyhole through a smoothbore shotgun barrel in my experience, but even with one in each three-shot group doing that, they still held a best of a little over 3 inches. A side note: Saboted “slugs” are designed for rifled barrels, and even though the idea behind them is actual jacketed bullet expansion that obviously can’t occur if the bullet enters a target sideways, a 385-grain keyholing projectile doesn’t need to expand to produce maximum effect on a target downrange.
This degree of accuracy indicates the Aimpoint CompM4s and Benelli M4 Tactical combo could easily carry beyond 50 yards, if needed, and the 25-yard zero produced group averages of 2 to 3 inches above point-of-aim at 50 yards.
Using the same zero, I moved in closer for 00 buckshot patterns firing one sample of each of three loads at 7, 15, and 25 yards on a B27 silhouette target. Buckshot patterns are generally a function of barrel choke and velocity. The Benelli’s cylinder bore barrel being essentially chokeless, I’d expected wider patterning. The shotgun and Winchester’s lower velocity Ranger law enforcement buckshots were consistently the tightest at all three distances, and it could easily have extended their usable range to at least 30 yards in keeping all 9 pellets inside the black and would have been a top choice if they’d cycled reliably. Federal’s 9-pellet Tactical load was next, followed by Remington’s 8-pellet Tac 8 rounds. All three were perfectly viable to 25 yards, which is not always the case in other smoothbores and other loads.
Military-grade hardware is usually pretty tough, and the Benelli M4 is no exception. If you can get past the price, and you either need or want tier one performance, you’ll get it from this shotgun and the Aimpoint sight.
In passing, the camo is a film layer process applied over a phosphate base at the plant in Italy, and it’s the same hard-use finish that Benelli uses on their duck guns. There are no other sight options offered, and the company can’t sell a Benelli magazine extension to civilians because it violates import restrictions. (Law enforcement and governmental agencies can buy a black extension for official use.)
The factory-installed choke can be swapped for other Benelli chokes with the tool included. One consideration for law enforcement users is that the process to render the M4 “cruiser safe” for vehicle duty involves cocking the shotgun, loading the magazine, and then pulling the trigger to de-cock the action for full-magazine, empty chamber, ready-to-roll carry. Pay attention when you do this!
Feed the Benelli right, change the battery on the Aimpoint every eight years or so, and you’re good to go.
The Benelli M4 semi-auto 12-gauge is considered by many serious users to be the…
by Jenny Gurvich and Tracy Liu / Apr 23, 2009