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Designing the Ideal 3-Gun Shotgun

A reliable shotgun is crucial in 3-gun competitions.

9/22/2011

Three-gun is the most addictive competitive shooting sport I have tried—and is one of the reasons I will likely die broke. This sport is highly equipment-driven, so I decided to develop and build what I think is the best trio of firearms for competing in the Tactical Optics (TO) Division.

In the fast-action world of 3-gun shooting, the shotgun is both the hero and the villain. It can help you win the match, or it can reduce you to tears of frustration. Time and time again, the top shooters tell me that many matches—particularly in TO—are won or lost with the shotgun.

There are many reasons for that. The shotgun is loaded on the clock, and in TO it is the only gun that requires rounds to be individually loaded. Some matches have extensive shotgun stages with as many as 40 targets. In Open Class, shooters can use speed loaders or magazines in the Russian Saiga shotguns, but in TO, they are prohibited. So when the shells must be fed one at a time, the match can switch from a shooting contest to a loading contest. If you can’t reload the shotgun faster than the other guy, you will almost surely lose.

Also, many 3-gun shooters come from handgun-action-shooting backgrounds. The USPSA shooters can typically pick up on the rifle technique easily, as it is similar to that of a handgun. Many of them lack shotgunning backgrounds, and they struggle with the moving targets and the techniques used to hit them.

The greatest factor of why shotguns can determine the outcome of a match, however, is reliability. Shotguns were not really designed to be used and abused the way they are in 3-gun shooting. I have witnessed far more equipment failures during a match with shotguns than with the other two firearms combined. I have seen shotguns stop working in spectacular fashion, from jams to total and catastrophic failure when parts of the gun fall out onto the ground.

When I started shooting 3-gun I used a gas-operated shotgun that had served me well in hunting, sporting clays, 5-stand and any other shotgun sport I tried. But, in the rough-and-tumble world of 3-gun, it quickly succumbed to failure, and not just once. I tried three different guns—including two different models—and I can’t recall getting through a single match without a problem. I have enough other problems to worry about in any 3-gun match, so I started paying attention to the guns that worked. I noticed that many of the top shooters were shooting Benelli guns. When I asked why, the universal answer was, “Because they work!”

A good part of the Benelli’s legendary reliability is due its inertia system that cycles the action. Gas-operated guns get dirty. When you are rapidly shooting hundreds of rounds in a single match, the carbon, fouling and unburned propellant mix with the dirt, dust or mud that is often part of this game, and the guns can grind to a halt. There is less propellant ejecta and other undesirable materials entering the operating system with each shot to build up and stall the shotgun. Of course, there are some excellent gas-operated shotguns being used in 3-gun, but nobody can deny that they all suffer from more carbon buildup than the Benelli. My goal was to build the ultimate three-gun battery with no-compromise firearms. For me, the path was clear, and I ordered a Benelli M2 with a 21-inch vent-rib barrel.

Of the three guns, at least for TO, the shotgun is the easiest for a hobby gunsmith to modify—up to a point. There are some modifications that go beyond the hobby stage. Some shotgun guys modify the return spring and the action by milling the bolt to lighten the weight. The idea is to increase its cyclic rate. Some of the top shotgun shooters can outrun any shotgun’s action, so they want a faster cyclic rate. According to tests done by my buddy Pat Kelly, who is one of the fastest guys with a shotgun, the Benelli is capable of 0.13-second split times between shots. My splits in competition run about 0.2 second to 0.16 second. Because of my phobia about total reliability, I decided to leave the gun’s operating system the way it was designed. I will leave the door open to modification if I ever improve enough to need a faster cyclic rate, but with my limited practice schedule and rapidly aging body, that’s probably not going to happen.

Few of us will ever get fast enough to outrun any shotgun. At the 2011 Superstition Mountain Mystery 3-gun match, I listened to one competitor explain an elaborate and complicated process of milling parts and pieces on the operating system for his Benelli shotgun. “If you do all that it will run without a hitch,” he smugly finished. The other guy looked at him like he had two heads and said, “It runs without a hitch right now, why on Earth would I want to mess with that?” I’m with that guy! I have seen too many modified shotguns fail in the middle of a stage, including several at that match.

Another common modification is to bevel the edges of the receiver in the shotgun’s loading port. The idea is to help funnel the shells into the gun as you are loading. It probably is a good idea, but I just have not brought myself to attack my gun with a milling machine or Dremel tool yet. Some shooters weld shut the gap in the front of the loading gate. They have problems with the Benelli pinching their thumb when loading. It has never happened to me, probably because of my loading style, so again I am going to leave it alone.

The one absolutely necessary modification is to add an extended magazine. I looked at a lot of magazine tube extensions before ordering the Nordic Components kit. I like the metal tube because I think it’s tougher and less prone to distortion from spring pressure or the barrel clamp. I also like the large metal clamp in the front that ties the barrel and magazine extension together. It’s rugged and large enough to spread the clamping forces over a large surface area, so there is less chance of distortion in the magazine tube or the barrel. A lot of problems with extended magazines come from the follower as it makes the transition past the joint between the magazine and the extension. The NC-anodized metal follower is Teflon-coated and works far better than a plastic follower. The plastic can become damaged and frayed, and it lacks the lubricity of the coated metal follower. Also, a plastic follower can bend or distort if it encounters resistance; metal will not.


The Int’l Multi Gun Ass’n (IMA) rules state that no more than nine shells total can be loaded at the start of a stage, so I originally elected to install an extension that would give me eight shots in the magazine. I have since learned about the benefits of a longer magazine with which you can load more than eight in the magazine after the stage starts, so I changed out to a 10-round magazine. So far it has run flawlessly in practice.

The spring that comes with the NC +5 (eight-shot total magazine capacity) kit is designed for this longer tube and is far too long for the eight shot. It must be trimmed to the correct length. One school of thought is to have just enough spring pressure to feed the last shell in the magazine into the action. But, that allows no margin of error. If there is a buildup of dirt, sand, or mud in the magazine, or if the shell has a burr on the rim or is distorted by an improperly seated wad or poor crimp, or if any one of a million other things are not perfect, there might not be enough pressure to push the shell into the action.

The need to apply a couple of ounces of more pressure on the shell as I am loading is an acceptable trade-off for the gun firing every time. So, by trial and error I cut the magazine spring so that when the gun is fully loaded I can push the ninth shell only about one-third of the way into the magazine. This gives me a margin of extra spring pressure to allow for all those aforementioned problems and to compensate for spring fatigue over time.

When I installed the magazine extension I put a drop of blue Loctite on the screws for the forward clamp. This allows me to remove the clamp for cleaning the gun, but keeps it in place during competition. I did not Loctite the fine threads on the magazine tube or the end cap, because I remove them often for cleaning and the fine threads do not respond well to Loctite buildup. But, I check them often during the match to ensure they are tight.

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5 Responses to Designing the Ideal 3-Gun Shotgun

John Herbert wrote:
January 14, 2012

Sorry but quality Gas guns are reliable, but you do need to clean them, they also have less felt recoil than inertia guns allowing you to shoot lighter loads with less recoil.

Steve wrote:
January 09, 2012

I use a Remington 1100 for my 3 gun matches. It is 38 years old. I have a Nordic mag. extension, Nordic charging handle, Dave's metal work ex loader, and a 23' barrel. It will shoot any load without failure. I have seen every manufacture of shotgun fail at the 3 gun matches including Benelli. My wife uses a Benelli for skeet, and yes it has failed more than once. She shoots an 1100 for trap and it has yet to fail. I like the Benelli but it is no better or no worse than the 1100. The gun I have seen fail he most is the FN SLP.

Bryce Towsley wrote:
January 07, 2012

I doubt the problems you are having are due to added weight of any magazine extension you might have added. That’s of course that is assuming you have not done anything out of the ordinary. More likely it’s a follower problem, but without seeing the gun it’s impossible to know for sure. I run a ten round Nordic Components magazine on a stock M2 and never have a problem. I also see hundreds more of these guns at the big matches and they all run fine. Of course you also need to use the correct ammo. A 3-dram, 1-1/8 ounce load should run without any trouble. If you go much lighter you run the risk of problems. That’s true with every semi-auto shotgun used in the game, not just Benelli. If the Mesa Tactical shell holder is installed correctly there are no problems. The problems are from the screws being tightened too much. However the Velcro shell holders like those from Mark Otto work very well and are much harder to screw up the installation.

Hooker wrote:
September 28, 2011

Wow, It just so happens that I added the same componets to my 24" M2 except for a +6 tube.But I'm having trouble with funtion due to what I believe is excessive weight and the Inertia system. Any easy fix, other then less weight?

Harmon wrote:
September 23, 2011

You forget one main thing: the shotshell holders are an INTEGRAL part of your reloading plan, best are AP Custom 4X4's. Also Benelli's have issues with the mesa sidesaddle, best to use a velcro one.