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So-called “sawed-off shotguns” have a long and legendary history going all the way back to the 1700s in original flintlock coach gun format, but we’re probably most familiar today with the short scatterguns carried by Chicago gangsters that led to the National Firearms Act (NFA) of 1934.

Current Regulations

Intended by Congress to deal with the popularity of certain high-profile weapons among the always-warring gangland factions and the new breed of motorized highway bandits of the early 1930s, the NFA generically lumped sawed-off shotguns with barrel lengths under 18 inches, rifles with barrels under 16 inches, full-auto machine guns and suppressors into one nationally regulated category requiring a specific federal process to go through for legal possession, including a $200 tax stamp.

This act accomplished several things, the most obvious of which was that it effectively removed legal possession of the affected items from reach of the everyday guy or gal who didn’t have $200 to spare in the middle of the Great Depression. The second most obvious effect was to add one more law for the professional lawbreaker to ignore who, then, just like today, tended to not bother registering their tools of the trade and drawing undue attention to themselves.

Since 1934, the Bureau of Alcohol, Tobacco, Firearms and Explosives (BAFTE) has taken a dim view of those who possess shotguns with barrels that fall under the length limits outlined in the NFA who haven’t gone through the official process of submitting two sets of fingerprints, a photo, a background check, a letter of approval by local law enforcement and a $200 check to the appropriate BATFE division. With the recently expanded market demand in short-barreled-shotguns (SBSs), short-barreled rifles (SBRs), and suppressors in recent years, the turnaround time for approval has risen from four months to roughly 12 months.

Sizing Down

We’ve traditionally gone by the government’s two length requirements to define an SBS: If it’s a shotgun with a sub-16-inch barrel, or has a total overall length of less than 26 inches, it’s an SBS regulated by the NFA. Seems simple, but let’s open up a big can of confusion and try to follow the regulations as they’ve evolved.

This SBS definition applies to modifying what started out as a normal shoulder-fired shotgun with a stock. Cut the barrel back on a regular shotgun to less than 16 inches without the tax stamp and you’re an instant criminal, regardless of what your intentions were. Chop off either end or both for the gun to be less than 26 inches overall, and you have the same result. An “Any Other Weapon” (AOW) category was also created to address smoothbore “handguns” easily concealable on the body that fall under a certain length but was manufactured as such from the get-go at the factory. An AOW still requires the same federal process, but the charge here is a mere $5, as opposed to $200.

Then Mossberg introduced the 590 Shockwave in early 2017. Calling it a “game-changer” would be putting it mildly.

Mossberg 590 Shockwave

If you’ve somehow managed to miss all the buzz on this one, the Shockwave is a 12-gauge variant of Mossberg’s tried-and-true 590 pump-action shotgun with a 14-inch barrel and black polymer furniture, including a Shockwave Raptor pistol grip. And you can buy it from your local gun shop—local ordinances permitting—with no more fuss and bother than you’d encounter in buying any other run-of-the-mill handgun or rifle. No fingerprints, no federal forms beyond the standard 4473, no year-long wait, no $200 tax stamp. Not even a $5 AOW stamp. How does this happen? Isn’t that 14-inch barrel an invitation to a stretch in a government vacation facility? Well, no. It turns out it’s all in the way the BATFE views it, and they gave it a green light. What’s the reasoning that makes it legal? Very simple: It’s not a shotgun. It’s simply a firearm. Huh?

In a March 2, 2017, letter, the BATFE declared that while the gun does indeed have a 14-inch barrel, it is not a shotgun in their eyes. They define it as a “firearm” because it is manufactured in such a way that prevents it from being fired from the shoulder. It doesn’t matter that it’s a smoothbore that shoots shotgun shells; the BATFE ruling on this model hinges solely on that non-shoulder-fired issue. From there, the firearm is also removed from any NFA regulations because it is slightly over 26 inches long overall. So this pistol-gripped firearm (PFG) sells, buys and possesses just like any other non-restricted firearm. That said, your state and local laws might have different definitions, so it’s important to check before you get your hopes up on this Mossberg.

Shocking Details

Now let’s get to the gun itself. As mentioned, this 5.25-pound pump is based on Mossberg’s long-running 590 series with a five-round magazine tube under a heavy-walled 14-inch barrel. The action is a standard bottom-loading side ejector, and you can directly load a round into the chamber through the right-side ejection port if needed. Twin action bars have always made the 590 a dependable cycler, and the quick and easy thumb safety up on top of the aluminum receiver is typically much preferred over the crossbolt-in-the-triggerguard type found on other brands.

The barrel and receiver have a dull, matte black finish. The polymer forend is ribbed along 4.5 inches of its length and features a very important nylon strap to keep your support hand from wandering too close to the muzzle while firing.
The Shockwave Raptor pistol grip is lightly textured to resist slippage under recoil, and sling swivel studs on it and the front magazine cap allow you to add a sling for hands-free carry. Finally, a medium-sized brass bead up front provides a frame of reference for aimed fire, and the grooved receiver top is drilled and tapped for an optic.

Test Parameters

I personally view PGFs as having certain limitations, and while you may agree or disagree, my shooting session was based on those limitations. So I took six test loads with me to the range, and none approached magnum levels. I have no problem going heavy with a shoulder-fired 12-gauge, but not with a stockless design. So my test ammo included four 00 buckshot loads 1-ounce slugs and some #8 shotshells.

I fired all of the 00 buckshot loads two-handed and otherwise unsupported from the hip for patterning on a black B-27 silhouette at 7 and 15 yards. Then I fired the slugs from the same position to gauge the shotgun’s recoil and controllability, and I tested the birdshot just to compare recoil levels. I also did a speed run at 5 yards, bracing the grip just inside my right hip and firing as fast as I could cycle the Mossberg.

You’ve undoubtedly noticed the absence of any eye-level aimed firing. I find any PGF to be awkward and unwieldy for aiming, and I value my face too much to bother. With practice and the necessary upper body strength, aimed fire can be practical out to 50 yards or so. Butt without the stability of a shoulder stock, it’s a relatively slow process, and there’s always the danger of facial reorganization with heavy loads. I’ll leave aimed fire to you; just keep the gun as far away from your face as you comfortably can.

Buckshot & Slugs

The Mossberg’s cylinder-bore barrel produced its two tightest spreads at 7 and 15 yards with Federal 00 buckshot. In my eyes tighter patterns are always better for defensive shotgunning. Both Remington 00 buckshot loads opened up markedly at 15 yards while still holding tight enough for headshots. Federal’s copper-plated TruBall slugs did what slugs do, creating a huge hole at any distance.

I didn’t have a problem controlling the Mossberg with both hands; the gun never jumped ship. But it did move offline enough on every shot to require a recovery period in cycling and reengaging the silhouette. At 7 yards, once I started to develop some muscle memory on the barrel elevation, it became easy to plant lead consistently inside the silhouette quickly. But moving out to 15 yards, I had a tendency to either overshoot or undershoot.

Overall, if you keep the limitations of the PGF in mind, the Shockwave can fit a niche. This is not a hundred-yard slugger. But on the other hand, it can travel unobtrusively in spots where a fully stocked 20-inch-barreled shotgun can’t. The action was a bit sluggish out of the box, but a good break-in would clear that up. With effort and the right load, the Mossberg is viable beyond 15 yards in a defensive situation.

Close Quarters

The Mossberg’s compact dimensions are very packable for transport and dynamic for close maneuvering. But resist the impulse to sling it under a trenchcoat with your favorite round-town fedora. The BATFE letter states, “Please note that if the subject firearm is concealed on a person, the classification with regard to the NFA may change.” Should they get wind of you doing it and decide to prosecute, your state CCW permit wouldn’t cover you there. I find a 12- or 14-inch-barreled shotgun with a folding stock more versatile. But that’s a Class III NFA weapon that requires BATFE notification in writing in advance anytime it crosses state lines. This Mossberg doesn’t have that problem, and it would make a great truck or home-defense gun where allowed. It’s also just plain cool.

Do your local legal due diligence first, and if you’re good to go, Mossberg can help you find a dealer. For more information, visit mossberg.com.

Mossberg 590 Shockwave Specifications

  • Gauge: 12
  • Barrel: 14.38 inches
  • Overall Length: 26.37 inches
  • Overall Weight: 5.25 pounds (empty)
  • Grip: Shockwave Raptor
  • Sights: Bead front
  • Action: Pump
  • Finish: Matte black
  • Overall Capacity: 5+1
  • MSRP: $455

Loads Tested

  • Remington 8-pellet Managed Recoil 00 Buck
  • Remington 9-pellet 00 Buck Ultimate Defense
  • Federal 9-pellet 00 Buck Personal Defense
  • Federal 9-pellet 00 Buck LE13200 Law Enforcement
  • Winchester AA Extra-Lite 1-oz #8 shot Target Load
  • Federal high-brass 1 1/8-oz #8 shot Heavy Field Load
  • Federal 1-oz Truball Deep Penetrator slug

This article is from the 2019 Gun Annual issue of Tactical-Life magazine. Grab your copy at OutdoorGroupStore.com. For digital editions, visit Amazon.

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