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Upgrading the military shotgun – part 2 – the barrel and history of use

Part one HERE.

There is at least 35,000 Mossberg shotguns in use by our military. Means there are at least 5 or 6 of these guns for every M1014 in use. So there are plenty of them stack away in various armories.

In the civilian world, the shotgun is seen as a very versatile tool. From hunting small game, big game, or self defense, we have a wide variety of options in ammo and configurations. The military not concerned about the hunting side of things. The shotgun was generally used for riot control, security forces, and breaching.

I’m told the Army has more Mossberg 500s for each Infantry Brigade than M240B machine guns.

Riot Control
Security Forces
Breaching

Using the Marine Corps as an example, in the past they used The Remington Model 11, Winchester Model 1897, Remington Model 10, Winchester Model 1912, and Ithaca 37 shotguns in the past. Eventually the Mossberg was adopted to replace all previous pump action shotguns.

It is often said that the Mossberg M590A1 is the only shotgun to pass the military torture test. This leads people to believe that the M590A1 model is the only one used by the miltary. Fact of the matter is that the M500A is used a great deal more than the 590.


Originally the military specified 3 types of shotguns for use:

The Type 1 was the classic trench gun with bayonet lug and capable of taking a heat shield. This is what we commonly see sold by Mossberg as the M590A1. Sources say about 1000 were purchased by the Army and USMC.

Type 2 shotguns are mostly 18.5 inch barreled M500 shotguns purchased by the Army. Older ones might be bright blued finished, later procured ones would be parkerized. Army choose to go with the plastic trigger group as they very rarely fail and it was decided it was cheaper to replace an entire trigger group than to attempt to repair or rebuild one. These are often standard M500A or M500 MILS shotguns.

Type 2 shotguns purchased by the Navy and USMC are M500 shotguns built to M590 specification using the 5+1 mag tube. Navy likes to buy 17 inch barreled models and the USMC often buys the 20 inch barrel length. These are often called M500A2 or M500M MILS shotguns. Heavy barrels, 590 style mag tubes, bead sights, metal safety and trigger group.

Type 3 shotguns are specified to have rifle sights. It is unknown if the military every bought any.

Navy 17 inch barreled M500
Army M500 where the stock has been replaced with a pistol grip

Let us not forget that the Mossberg shotguns share a common receiver. A 500 could be turned into a 590 by replacing parts, or the other way round. The majority of the parts also interchange with the Model 835 and Maverick 88.

With current use of military shotguns, they have primarily become a breaching tool. Functioning less as a weapon, but an additional piece of equipment for a soldier to carry.

I’m sure this guy just loves carrying two weapon systems.

You would think that breaching with a shotgun would be quick and easy. Shoot the lock, kick the door, enter.

Unfortunately there are any number of things that can go wrong. You need to be at the right angle and distance from the lock. You need to be able to see the lock. If there are multiple locks on the door, you need to be able to engage each one.

There are all sorts of things that can go wrong with breaching. When attempting to breach quickly and/or in the dark it can be hard to get the right stand off distance. Worst of all, you can end up bursting the barrel or having fragment come back and injure yourself or friendly troops.

On the left, a 20 inch M500 barrel, the right a 18.5 inch breacher barrel

That is why the military decided on a fixed breaching stand off. Tests were done on choke based or removeable standoffs but there were failures leading to the decision to go with a permanently mounted one.

This new barrel is approximately 16 1/4 inches in length with out the stand off. The permanently attached standoff brings the barrel to 18.5 inch overall length.

Now, there was a little problem trying to source this barrel. Mossberg is a major manufacturer of shotgun barrels. You can buy all manner of M500, M590, and 870 barrels from them.

590 style threaded cap on the left, 500 style screw in barrel on the right.

Your average Mossberg M500 uses a barrel that screws right in to the magazine tube. The average M590 uses a ring attached to the barrel that and a cap that screws onto the magazine tube. But, Mossberg has made 500s that use the 590 configuration, and 590s that use the M500 style barrels.

Generally, only “tactical” style barrels are available in the 590 setup. All the specialized hunting barrels are set up for the 500 system. Why Mossberg has two different styles of barrels is something I don’t understand. I would have thought they would have picked one system and discontinued the other long ago.

As I said, Mossberg makes all sorts of barrels. You can easily buy a M500 style breacher barrel from their website. You can even buy Mossberg manufactured 870 breacher barrel from their website. But, for some reason unknown to me, they do not list the 590 style breacher barrel for sale.

When I finally decided to pursue this project, I decided I would get the barrel first. I never imagined it would be such a pain in the ass to find one for sale. It finally got to the point where I was expecting to have to buy a whole additional shotgun that came from the factory with this barrel just to get the barrel. Fortunately I got contacted by Pro Patria, who sold me a used barrel as a good price. Around that time a used barrel of this model also showed up on ebay. There are a good many of them out there, but most all of them are mounted on guns.

Changing the barrel on the Mossberg shotgun is very easy. Unload the gun, open the action slightly. Unscrew the magazine cap (or on a M500 the screw on the barrel). Then slide the old barrel off. Slide the new on on and screw on the mag cap.

This new barrel is 1.5 inches shorter than the old barrel. While that is not much, it is enough now to let me case the gun in my 33in rifle case with out disassembling it. That is convenient.

The bead front sight is replaced with a white dot front sight. This sight screws in place of the brass bead and has a white plastic insert. I’m undecided if that is really a worth while upgrade or not. There is a tiny gap between the base of the sight and the barrel and I question if it is any more durable than the bead sight.

But, most of the bead sights on the shotguns I used in the Corps were broken off, so having a front sight is already an improvement.

In the next section I’ll talk about the rail system.

Upgrading the military shotgun – Part 1 – Pointless Rambling

Part 2 HERE.

Alright, I was going to wait until the project was complete and post a short and sweet, concise, article about it. But now the last part I ordered is indefinitely delayed, I’m going to drag this out.

Later on I am going to talk about equipment, military usage of the shotgun, and various possibly interesting things, but that won’t be in this post. This post is just me rambling.

I don’t like shotguns. I don’t like them so much that I only own five of them. If anyone ever needed any evidence that I don’t like shotguns, that should be damning enough in it self.

When I found out that there were some contract over runs of the Mossberg model we used while I was in, I picked up one. Hey, if I was going to have a shotgun, I want it to be something somewhat special.

Mossberg M500M MILS

Some would say that every red bloodied American should own a shotgun, and those people would be wrong. But if you are a gun nut, you probably want to have at least a pump shotgun around, and the 500M MILS fit that niche for me. Something I could pull out once or twice a year, shoot, and remember why I don’t like shotguns.

For example, recently I have been doing 50 yard shooting with buckshot. I would be left wondering where the hell all the pellets are going. Shooting at an 8 inch bullseye, I would be left with only a few two pellets strikes in the black after firing multiple shots down range.

Now, kinda off topic, like a bulimic, I binge and purge my collection. I’ll spend a while buying up stuff I think I will like, then at some point, realize I have a guns, optics, and accessories I don’t like or don’t use, so I sell off that stuff. I sell it off to get money to spend on other stuff I won’t like or use. You will hear more about that soon.

The M500M is a keeper as it fits a niche my other guns don’t. That is, being a pump action shotgun. It is also a keeper as it has sentimental value of the very rare times I used a shotgun in the Corps.

Back in 2017ish the USMC announced that they were upgrading their pump shotguns into the “M500A2 MEK”

I’ll go into detail about the kits and the parts later.

I saw this, and was kinda tempted to reproduce the kit for my Mossberg. But rational thought prevailed and I didn’t.

I kept telling my self that I would be spending a good bit of money on a gun I rarely use, to change it into a configuration that I would shoot even less. It would be silly of be to waste my money doing this.

For about 3 years I told my self that. But then I had a thought. A worrisome idea that repeated like an earworm. What if I was becoming one of those old fogies spouting off non-sense like, “my wood and blued steel”? What if I was bypassing a major upgrade because I was comfortable with my old and obsolete clunker? *Gasp* What if I was acting like a M14 fan?

Of course not, but now I had an excuse to waste my money on this ‘upgrade’.

The parts of the Military Enhancement Kit were mostly easily available. Any conversion would be reversible if I didn’t like it or wanted to return to the stock configuration. And most of all, I had just sold some gun stuff I didn’t like and was ready to blow some money on something else I wouldn’t like.

I figured the heart of this conversion is the barrel, so I started looking for a barrel. I’ll talk about the barrel in part 2.

Using the Mantis X10 to compare recoil on three shotguns

Mossberg M500M MILS, Benelli M1014 Flag Edition, Molot VEPR-12

I’d been telling people that I think my Benelli M1014 has more felt recoil than my other shotguns. I’d been getting responses like, “You must be joking“, “What an idiot“, “a semi would never have more recoil than a pump“, “ur a fuckwit“, etc.

Well lucky for me the people at Mantis asked me to write a review of the X10. I’m working on that. (Spoiler, I like it!) One of the many features of the X10 is a “Recoilmeter”. Now I want to compare my .45 ACP Glock 30 vs my Colt 1911 in recoil. I want to see how the Glock compares to the P320, etc. But I really wanted to see how these shotguns compared.

I was able to use the adapter that comes with the X10 to clamp to to the Mossberg M500’s barrel. This clamp also worked on the Benelli’s mag tube. I was able to install the X10 right to the rail on the gas block of the Molot VEPR-12.

I fired four shots of Winchester 00 buckshot from each gun. For our purposes I am going to use the numbers from the first 3 shots of each test. We will throw out the 4th shot as on two of the guns the action locked open and what we really care about is recoil between shots. And. . I didn’t have the clamp tight enough on the Mossberg for the last shot and the whole unit slipped forwards.

It is not really a fair comparison, as one is a pump. I tried to have the Mantis X10 in as similar a position on each gun as possible. I tried to keep things as comparable as possible. Shooting was done at a rapid pace. I use a 8 inch repair bull target at 50 yards for my point of aim. The X10 records and tells us a variety of different info from each shot.

Side note, the grey line you see going off to the upper right on each image is the movement of my last shot, the 4th one, which included moving the gun off target afterwards.

When firing the pump action Mossberg, the muzzle rise record by the Mantis X10 clocked in at 2.40, 2.05, and 1.25 degrees. This is an average of 1.9 degrees of muzzle rise across the three shots. Interestingly enough, the movement of the gun tended to be more up and left vs the up and right as often see with firearms fired right handed. This is shown by the negative “Recoil Angle” that is in the MantisX app.

Shooting 12 gauge buck shot out of a pump action has noticeable recoil. I’m not particularly recoil sensitive, but I have injured both my shoulders in the past, so I tend to prefer not to shoot higher recoiling guns any more. Still I could shoot this Mossberg all day long. You feel the recoil, but double-naught buck is not unpleasant out of this gun.

Firing the Benelli M1014 flag edition clocked in a muzzle rise of 4.30, 4.93, and 4.82 degrees. This is an average of about 4.7 degrees. Over DOUBLE the muzzle flip of the pump action Mossberg.

HA! Who is crazy now?

The Benelli classically recoils up and right like your average longarm for a right handed shooter. About a 30 degree angle up and right as shown by the MantisX app.

This increased muzzle flip is really noticeable as the firearm was coming up and off the 50 yard target between shots. While the Benelli has superior sights, I had to reacquire the target and realign the sights between each shot.

Now to keep things interesting, I also tested my Molot VEPR-12. I’ve often told people how surprisingly pleasant the VEPR-12 is to shoot. I can use lightly loaded shells and 3 inch slugs in the same magazine and it will cycle them all and still be pleasant to shoot. It will reliably cycle lightweight loads that make the M1014 jam.

The X10 recorded muzzle rise of -0.19, 1.07, and -0.22 degrees. This gives up an average of 0.22 degrees of muzzle rise across the three shots. Big difference between shooting this shotgun and others.

Now this shotgun does have a large muzzle brake on it. It was really pleasant to shoot before the brake, and the brake certainly doesn’t hurt. These particular Mossberg and Benelli guns have no accommodations for a choke or brake.

On a tangent, note that after the last shot on the VEPR-12, I was just lowering the muzzle like had I been firing an AR15.

Now I know some of you are saying, “Hey, that recovery time listed is higher on the Vepr-12.” You would be right. The VERP-12 averaged 1.01s over the .89 seconds of the M1014. This is a difference of over a tenth of a second. I’m not sure what happened there. If it was due to the AK style sights or if I was just shooting slower after being abused by the Benelli.

Now this isn’t a definitive test, it is a small sample size of shots with just me as the shooter. We only see the recorded muzzle flip and it says nothing about the overall recoil impulse. But is is nice to have some hard numbers showing that my Benelli moves more during shooting that my other shotguns, even the pump action.

More unnecessary ranting below:

Read moreUsing the Mantis X10 to compare recoil on three shotguns

M1014 and VEPR-12

For some time I had wanted to get a Benelli M4 Super 90 (M1014) and figured I’d sell my VEPR-12 after I picked up the Benelli. Molot VEPR-12s are no longer imported, and I am concerned about spare part and magazine availability. I liked the idea of the Benelli having the self contained tubular magazine where I wouldn’t need to worry about accessories. I thought the M4 Super 90 would be an excellent choice due to its’ proven performance, reliability, etc. I traded for a customized limited edition (the flag edition) M1014 model of the M4 Super 90 line.

While I was waiting on the shotgun to come in to my dealer, I read so much about them. The operation, history, manuals, etc. So many people talked about how it will reliably feed any ammo and is so light recoiling.

I wonder now if the people who said that actually shot one. It recoils like a pump action. Shooting the VEPR-12 and the M1014 side by side the VEPR move so much less. Shooting the VEPR-12 is like shooting a standard AK. Shooting the M1014 reminds me of when I had a .45-70 guide gun. Not unpleasant, but moves a great deal with the recoil of every shot. I can shoot the VEPR-12 fast and the barrel stays level and the sights on target.

I would have probably would like the Benelli a great deal more had I never shot a Vepr-12. But I can load 3 inch slugs and extra-light bird shot in the mag of the Vepr-12 and it runs it fine due to its’ self adjusting gas system. The M1014 chokes on light loads and makes heavy loads borderline unpleasant to shoot.

Now, I’m not so sure I’m going to keep that Benelli. I might just sell or trade it off and leave the Molot Vepr-12 as my semi-auto shotgun.

Benelli M1014 Flag Edition

Finally got it set up the way I want it. had to replace the Surefire railed handguard with the standard forend and I removed the Taran Tactical enlarged bolt release button and installed a standard bolt release.

The bolt release button is also the catch that holds the shells in place when you load the tube. The bolt release that was modified with the Taran Tactical bolt release was very stiff to insert shells into the gun. I wonder if it got bent slightly in the installation of the enlarged button. The stock catch makes for easy loading.