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Impact Munitions: Time to Go Big Bore?

Many police agencies have recognized the benefit of having a less-lethal munitions option immediately available to uniform patrol officers.

These agencies have recognized that as effective as the TASER® can be, it is always beneficial to have additional use-of-force options available. A patrol-based less-lethal munitions program provides a comprehensive less-lethal response option for the uniformed officer.

The majority of these programs are based on the application of the 12-gauge shotgun, which is considered a “small bore” launching platform. The 12-gauge specialty impact munitions today have achieved a level of advancement in accuracy and construction that was previously only wished for. Gone are the days of the square shot-bag rounds flying off in directions that were neither intended nor anticipated. Or square bags that would not unfold and strike edge-on and penetrate the skin.

Today we have a variety of flexible and non-flexible rounds that are single or multiple projectile in nature; are tail, fin, spin and drag stabilized; and display impressive accuracy with very little recoil or report. All of them are non-penetrating, assuming they are deployed from the correct ranges.

Even as the 12-gauge specialty impact rounds have improved, the manufacturers of less-lethal munitions continued to develop and improve on what we consider the “Big Bore” launching platforms—the 37mm and 40mm launchers. The accuracy of most big bore rounds today is better than the 12-gauge rounds. Some platforms use rifle-stabilizing barrels, which are extremely accurate. Of course, the effectiveness of the big bore rounds on targets is far above and beyond that of the 12 gauge. It is probably time to give serious consideration to switching to the big bore platform.

Why Go Big Bore?

So what is the attraction of the big bore launching platform? What are the advantages over the small bore launchers? Energy is mass times the square of velocity. That means if you want to have more impact energy from your less-lethal munitions, you either have to increase the weight or the speed of the projectile.

However, with less-lethal munitions against humans, it is not quite that simple. You can’t increase the energy beyond the point where the projectile begins to penetrate soft tissue. Most 12-gauge impact munitions are right at that upper limit of energy. The solution is to spread that energy over a greater cross section. You want to spread the force over a larger impact area, not to impact a greater area of tissue, but to allow higher levels of energy without penetrating the skin.

Remember this high school math question: Which applies more pounds-per-square-inch of force to damage a linoleum floor, the high heel of a 120-pound woman or the hoof of a 4-ton elephant? Yep, in terms of pounds per square inch, it is the woman’s high heel. All that pressure from the elephant is spread across a larger area. Big bore rounds pack much more punch, deliver greater force, and carry greater weight and mass to the target.

Not surprisingly, based on after-action reports, small bore less-lethal engagements require an average of four rounds to address the threat, while the big bore munitions take an average of two rounds to be effective. We also know that with regard to injury, it is the application of the small bore munitions that have resulted in the greatest number of injuries to suspects during the past decade. This is because the small bore munitions have greater potential to achieve penetration due primarily to the smaller cross section of the round.

Perhaps most importantly, some (but not all) big bore launching platforms, when combined with the appropriate munitions, have impressive range and accuracy versus the small bore launchers and munitions. Shorter engagements also result in less potential exposure to risk for officers, bystanders and hostages, as well as offenders. We always want to stop the threat as quickly and efficiently as possible. The big bore munitions are safer and more effective for all involved; risk and liability are reduced.

37mm or 40mm?

When considering the big bore launcher, the first decision that must be made is whether to go with a smooth bore 37mm, a rifled 37mm or a rifled 40mm launcher. The immediate benefit of the rifled barrel is the level of both range and accuracy that the smooth bore 37mm simply can’t begin to match.

Remember that with less-lethal munitions, the accuracy determines the usable range of the launcher. The projectile may be effective at longer ranges, but the risk of the projectile striking a no-hit danger zone limits the use to where these zones are outside the radius of hit probability. A more accurate less-lethal launcher has a longer usable range.

If you are looking for a compact big bore launcher for short range applications and the launching of gas and smoke, a smooth bore 37mm can come in handy. Of course, there are additional options to consider when using proprietary launchers such as the Sage and the Arwen. The Arwen is an outstanding 37mm rifled launching platform with an excellent construction and fine pedigree. However, there are disadvantages as well. The Arwen is expensive— its munitions are not only expensive, they are proprietary and can only be launched from an Arwen launcher. If the Arwen should happen to break, fixing it may become difficult. If money is simply no object, the Arwen is an excellent platform.

The Sage 37mm rifled barrel launcher has some similar issues to those of the Arwen. The Sage launcher is also an excellent device that is well made and highly accurate. It utilizes a proprietary munition that will function in the Sage and, interestingly enough, the Arwen, but no other manufacturers’ launchers. Sage does make a 40mm launcher that will accept all forms of 40mm munitions.

Big Bore Weaknesses

As good as the big bore platforms are, they aren’t perfect. The number one detriment in utilizing the big bore launcher is in the use of the hinged breech, single-shot launcher. No matter how much you train, though you may get fast at reloading, it still may not be fast enough. This is not an issue if you can afford to obtain a 37mm or 40mm multilauncher, either spring-wound or pump-action. However, they are significantly more expensive than the single-shot versions.

There are some innovative and smart methods for carrying additional rounds in close proximity that expedite the reload process. Magnum Tactical makes an outstanding nylon buttstock carrier for 37mm or 40mm rounds, as well as outstanding drop leg carriers and pouches. Some smart barrel mount systems are available to carry additional rounds close at hand that would seem to work well.

Putting a big bore launcher in every patrol car is simply cost prohibitive, even for the wealthiest agencies. This means it is more likely that big bore launchers will be “pool” launchers, shared from shift to shift, or that there will be fewer launchers per shift as compared to a 12-gauge program.

To develop a reliable level of expertise, officers must train consistently with any tool or device, and less-lethal launchers are no exception. Training can become costly when using the big bore platforms. Those agencies utilizing a 37mm or 40mm launcher will find that many manufacturers offer training “kits” that including reloadable heads and bases. Another option is to purchase and rotate munitions based on age from field-ready to training stock, as we do with handgun and rifle ammunition.

Munitions Selection

When transitioning to the big bore less-lethal platform, you will have a wide selection of impact rounds. Just pick the mix of projectiles that best suits the needs of your agency, whether it’s flexible or non-flexible. Consider your environment and probable missions, and you’ll likely find several rounds that will fit your particular needs.

Each agency must do its homework on the advantages and disadvantages of going big bore. But know this: Adopting a big bore platform can provide significant enforcement improvements versus a 12-gauge-based program.

Rob DeGroot is a 27-year law enforcement veteran and Master Peace Officer in the state of Texas, where he still works in law enforcement. He is an active instructor and educator and is one of four master instructors for ALS Technologies nationwide. Rob is currently instructing and consulting for Leadership Systems LLC and Cogent Services Inc. If you have questions or inquiries or would like assistance with training-related issues or topics, he can be reached at

Published in Tactical Response, May/Jun 2011

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