Benelli M2 vs M4: Italian Inertia vs Gas Scatterguns

by Travis Pike

May 11, 2023



Benelli didn’t start life making shotguns. In fact, they became known for their motorcycles before their shotguns. Somehow, they drifted into the world of firearms and did it incredibly well. Benelli shotguns cracked the code on semi-automatic designs. Today we are going to put two of the best head to head, the Benelli M2 vs M4.

When the original Benelli M1 came out, semi-auto shotguns had been on the market for close to a century. At the time, people were skeptical about using semi-auto shotguns for any defensive or duty use. With the Benelli M1, that changed. 

Benelli quickly became the masters of semi-auto shotguns, and they’ve become one of the most trusted names in repeating claymores. Their shotguns vary widely from the Super 90 series designed for police, military, and home defenders to their beautiful sporting guns. 

Two of their most popular guns are the Benelli M2 and Benelli M4 series. Today we are going to compare and contrast the two guns to see which might be the right choice for you. 

History of the M2 

They predictably built the M2 on the Benelli M1. The Benelli M1 used a recoil system designed by HK, which first made its debut in the HK512. However, the Benelli M2 is an inertia-driven gun available in a multitude of configurations. The M1 was the first gun to really make a positive impression of semi-auto shotguns on the duty and home defense market. 

The M2 hit the market in the 1980s and became a near-instant hit. Benelli received contracts for police and military forces around the world, including the Italian Carabinieri, the Irish Army, the UK Army, and many more. 

The differences between the M1 and M2 are seemingly few, but are important. The M2 introduced the Crio-treated barrel, which is supposed to make the barrel tougher and improve patterns. Additionally, they changed the chokes to make them longer and more effective. The M2 also features the recoil-reducing padded chevron system in the stock. The M2 Stock also utilized an adjustable LOP and a shim kit for drop and cast adjustments. 

Since then, it’s easy to say that the M2 is Benelli’s flagship shotgun and seemingly the favorite child of the brand. 

Benelli M2 Variants

The M2 comes in many variants in both 20 and 12 gauge, something the M4 does not. Below are the performance 3 gun and the tactical version of the M2.

History of the M4

With the M4, Benelli broke its own mold. Benelli is well known for their inertia-operated shotguns, but with the M4, they leaned into gas operation. Gas-operated shotguns were nothing new, but they weren’t Benelli’s bag. Benelli specifically made the M4 when the US military went shopping for a shotgun. The United States Marine Corps was tasked with finding the next shotgun for military use. 

The Marine Corps went to Benelli with their requirements, and they produced the M4. The gas-operated system ensured the heavy night vision optics were compatible with the gun. They also wanted an adjustable stock so they could use the gun with armor and a rail for optics. Obviously, they also wanted a semi-auto design. 

Benelli developed the M4 and the ARGO system to be the most reliable form of gas operation out there. The Benelli M4 went on to become the M1014 Joint Service Shotgun. The shotgun also found success with major police agencies like the LAPD. Outside of the United States, the M4 would go on to serve with numerous military forces in Italy, Israel, the UK, and many, many more. 

The M4 is one of my favorite shotguns.  Check out our full Benelli M4 review.

Benelli M4 Variants

The M4 is only offered in 12 gauge, in two different colors, and a few different stock configurations plus the M1014 for civilians.

Benelli M2 vs M4 Spec Comparison

Benelli M2 Featured Image

Benelli M2

Caliber 12 Gauge
Action Semi Auto
Action Inertia-Driven
Capacity 3+1
Weight 6.7 lbs
Check Price

Benelli M4

  • Final Grade : B
Caliber 12 Gauge
Action Semi Auto
Action Auto-Regulating Gas-Operated (A.R.G.O.)
Capacity 5+1
Weight 7.8 lbs
Check Price

Inertia vs. Gas 

When we start comparing the two guns, a big part of the discussion comes down to the difference between a gas-operated and an inertia-operated system. Both systems have their advantages and downsides, and it’s tough to say one is inherently better than the other. 

Inertia systems seem like feats of engineering. I understand gas operation easily, but inertia systems impressed me. Benelli’s inertia system When a gun’s fired, the recoil begins to make everything move rearward. If a part is not fixed, it doesn’t move, and the Benelli bolt body does not move. It stays put as the rest of the gun moves rearward. 

This creates a difference in motion between the bolt body and the rest of the gun. This difference in motion compresses a very strong spring that sits between the bolt head and body bolt. Once the recoil impulse lessens and the shot leaves the barrel, the spring rebounds. That rebounding force throws the bolt rearward and completes the cycle of operation. 

A gas system is much simpler and easier to understand to my crayon-eating brain. When gunpowder ignites, it creates gas. That gas propels your projectiles forward. A gas system siphons some of that gas, and with the Benelli M4, the gas throws two gas pistons rearward to strike the bolt and complete the cycle of operations. Much simpler. 

Both methods of operation tend to be very reliable. The gas-operated guns do offer less recoil, which is advantageous. However, they tend to be heavier and bulkier than the lithe inertia guns. Gas-operated guns can also function with added weight. 

Adding optics, side saddles, and similar items will not inhibit their reliability. Inertia guns require the shotgun to be a certain weight because the recoil is a big part of the gun’s operation. If you increase the weight, you decrease the reliability. 

Gas guns do require the user to clean the gun more often than inertia guns. They also have more parts and pieces that need to be cleaned. Inertia guns tend to be much simpler to clean and need cleaning less often. Inertia guns do require the gun to be braced into your shoulder to function properly. Gas guns are not so picky. For most of us, that’s not a big deal, but for breachers and similar special purpose roles, it can be a deal breaker. 

Variety of Guns 

Depending on what you want to do with the gun will make a big difference in your decision. If you want a home defense gun, then the M4 and M2 both offer short, lightweight options with 18.5-inch barrels and numerous stock configurations. That’s great, but if you want a hunting or competition shotgun, then you have to turn to the M2 series. 

The M2 comes in a field model, a slug gun, a turkey gun, a waterfowl gun, and a 3-Gun competition model. You can also get a 20-gauge model if you need something smaller and lighter. 

Benelli’s M4 comes in two configurations. The M4 tactical and the M1014, a neutered version of the military’s gun. The M4 only comes in 12 gauge, and you can pick between a standard stock and a stock with a pistol grip, and that’s it. 

Benelli M2 vs M4 Options Winner


This is the golden question. Which semi-auto shotgun is more reliable? The M2 and its inertia system aren’t as maintenance heavy as the M4 and its gas system. However, the M4 gas system is unlike other gas systems and uses a self-cleaning dual piston that does function extremely well in the harshest conditions and after thousands and thousands of rounds. 

The M2 is picky about how it’s shouldered, and any weight added, which does take the reliability score down a notch or two. The M4 and gas-operated shotguns, in general, tend to function better with lighter-loaded rounds to an extent. So much so that the M4 can handle 2.5-inch short shells. However, we are looking at two guns that are widely considered to be the pinnacle of semi-auto shotguns. If the M4 is a 10 out of 10, then the M2 is a 9.8. 

Both guns are reliable and will serve you well. If you need a gun to go to Fallujah, take the M4. If not, maybe the lighter, handier M2 better suits your needs. 

Benelli M2 vs M4 Reliability Winner


Side by side, you will notice a difference between the M2 and M4 series shotguns. Gas operation takes a chunk of gas away from the gun to cycle the action. This helps reduce recoil and makes the gun easier to control. Additionally, the extra weight of the gas-operated gun helps reduce some recoil just by principle. 

The inertia system of the M2 isn’t going to rock you, but the difference is noticeable. A pump shotgun has significantly more recoil than the M2, and as a semi-auto, it naturally takes a little sting out of a 12 gauge. Benelli’s Comfortech stock does remove some sting from the gun as well. If you want something lighter, recoiling the M2 does offer the 20 gauge option. A 20 gauge M2 is downright amusing to shoot and has significantly lower recoil than the 12 gauge. 

The M4 still takes the cake when you compare 12 gauge guns, but the M2 in 20 gauge will offer the most reduced recoil for your buck.  

Benelli M2 vs M4 Recoil Winner

Ease of Use 

Both guns have a fairly standard layout. You load your rounds into a tubular magazine, work the charging handle to load the gun, and pull the trigger. The safeties are similar and as are the standard ergonomics. There isn’t a huge difference in the general operation of the weapons. 

The biggest difference comes down to cleaning these guns. Benelli’s M4 has a bit more to clean with gas ports, gas pistons, bolts, as well as the inside of the receiver. The M2 inertia system requires fewer parts overall, and cleaning and disassembling the gun is much easier. 

Benelli M2 vs M4 Ease of Use Winner


If you want to accessorize your shotgun, you might need to take a careful look at what you want to add to the gun. When it comes to adding accessories, the M2 can easily receive one of the modern micro red dots, a side-saddle, a light, and maybe a magazine extension tube. However, you might have to be cautious when you start adding all that weight. It takes quite a bit to make the gun malfunction, but you should ensure everything works as is before you depend on it for defensive use. 

You could add a boat anchor to the M4, and it won’t care. The Marine Corps wanted a gas system that allowed them to use the massive thermal and night vision optics of the era. These easily added pounds to the gun, and on an inertia weapon, may have become an issue. Put a 10-50 scope on it. It doesn’t care. 

On the flip side, the M2 has been around a lot longer, and there are likely a lot more M2s out there than M4s. With that in mind, the M2 aftermarket is much larger than the M4. There are more stocks, magazine extensions, charging handles, optics options, and more out there for the M2. The M4 lacks that same aftermarket. As an M4 owner, it can be frustrating to even find enough parts to become 922R compliant. 

The M2 has tons of accessories available, including the XRail system, which introduced a 25-round rotating magazine for the gun. 

Benelli M2 vs M4 Accessorization


When it comes time to shop for a semi-auto shotgun, you best expect to separate yourself from some serious dinero. Especially if you are going to start shopping for Italian shotguns, they aren’t cheap by any means. With that said, the M2 is much cheaper. The M2 Tactical starts with an MSRP of 1,249, and the Benelli M4 starts with an MSRP of 2,099. That’s a big price jump and one that might be tough for some to justify. 

Benelli M2 vs M4 Price Winner

What About the M3?

We’ve talked about the M2 and M4, but is there an M3? Yes, the M3 is essentially an M2 with the added option to cycle the gun manually as a pump-action shotgun. It’s neat, but it would fall on the side of the M2 if we introduced it to this competition. 

Spaghetti Blasters For All 

Italians have taken shotgun gold. Beretta now owns Benelli, as well as Stoeger and Franchi. This gives them a massive amount of control over the tactical market. Their semi-autos dominate the conversation, and the M2 and M4 are a big part of that. Sure the 1301 might be the new hotness, but they proved the M2 and M4 in more ways than one. Being armed with either means you have a top-tier shotgun that’s dependable, capable, and quite powerful. 

And The Winner of Benelli M2 vs M4

It really depends on your use case, but the Benelli M2 came out on top. If you are needing a dedicated tactical shotgun and have some money to spend, the M4 would be the winner. But as an all around shotgun, we are giving it to the Benelli M2. You can get it in tactical, competition, and field versions where the M4 only has tactical offerings.

While I tend to be more of an M4 fan, the M2 does offer some advantages, and you certainly wouldn’t be under-armed with an M2. Which would you choose? Let us know below! 


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About Travis Pike

Travis is a former United States Marine Corps Infantryman and currently a firearms writer, instructor, and works in Emergency Management.

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