There’s a certain satisfaction that comes from handling a tool built for a specific purpose, especially when that purpose is delivering reliable, close-quarters performance without the paperwork. The Mossberg 590 Shockwave 20 Gauge isn’t trying to be a sporting clays gun or a waterfowl hunter’s primary. It’s a compact, no-nonsense platform that leverages Mossberg’s proven 590-series DNA into a highly maneuverable package. For the DIY enthusiast or the tinkerer who appreciates mechanical simplicity and robust construction, this 20-gauge variant offers a compelling blend of reduced recoil and the legendary durability you expect from the brand. The 14.38-inch barrel and Raptor pistol grip define its profile, creating a firearm that’s as much about utility and personalization as it is about immediate readiness.
Miamishooterssupply is a Boise, ID-based retailer specializing in firearms and shooting gear for the serious enthusiast. The Mossberg 590 Shockwave 20 Gauge 3in Blued Pump Action Firearm – 14.38in is a compact, non-NFA firearm built on Mossberg’s heavy-duty 590 action. Its 20-gauge chambering makes it more manageable than its 12-gauge counterpart while retaining formidable close-range capability. This model is in stock and ready to ship today for $239.99, a significant saving from its regular $299.99 price.
Reviewed by Cody Ramirez, E-Commerce Director at Miamishooterssupply. 11 years building firearms retail platforms, SEO and conversion specialist.
Last updated: March 2026
Built on a Proven Foundation: The 590 Action
At its core, this isn’t a novelty item; it’s a Mossberg 590. That means it starts with a dual-action bar system, a steel-to-steel lockup at the bolt, and a receiver machined from a solid block of aluminum. From an armorer’s perspective, this is critical. The dual-action bars prevent binding and provide a smoother, more reliable pump stroke under stress—a feature often highlighted in law enforcement and military evaluations of the 590 platform. The 20-gauge chambering uses a scaled-down version of this robust system, so you’re getting the same engineering principles in a lighter-recoiling format. The 3-inch chamber gives you flexibility with shell selection, from light target loads to heavier defensive options.
The Shockwave Configuration: Form Follows Function
The defining characteristic is, of course, the 14.38-inch barrel and the Raptor-style pistol grip. This configuration, utilizing a stabilizing brace or being fired from the hip, creates a package with an overall length under 27 inches. The balance point is directly over the grip, making it incredibly quick to point and maneuver in tight spaces. The bead sight is simple and effective for its intended range. The blued finish on the barrel and receiver provides a classic, durable corrosion resistance that’s easy to maintain. It’s a no-frills setup that prioritizes handling and reliability over aesthetics, which is exactly what you want from a tool in this category.
Handling and Customization Potential
Where this platform really shines for our audience is in its potential as a starting point. The 590 series has massive aftermarket support. The 6-round tubular magazine is a good start, and the receiver is pre-drilled and tapped for optic mounts. The pistol grip can be swapped, and the entire forend can be upgraded to M-LOK compatible units for adding lights or lasers. The 20-gauge recoil is noticeably milder than the 12-gauge Shockwave, making extended practice sessions more practical. This is a firearm that invites you to make it your own, whether that’s adding a simple sling mount or going full custom with a new stock system (where legally compliant).
Pros and Cons: An Honest Assessment
✅ Pros:
- Proven 590 Reliability: Built on the same heavy-duty, dual-action bar system trusted by military and law enforcement.
- Manageable Recoil: The 20-gauge chambering significantly reduces felt recoil compared to the 12-gauge model, improving control and shootability.
- Exceptional Maneuverability: The compact 14.38-inch barrel and pistol grip design make it ideal for close-quarters handling and vehicle storage.
- Strong Aftermarket Support: As part of the vast 590/500 series ecosystem, virtually every component can be upgraded or replaced.
- Excellent Value at Sale Price: At $239.99, you’re getting genuine Mossberg quality and durability at an entry-level price point.
❌ Cons:
- Specific Shooting Technique Required: The Raptor grip demands a specific, practiced hold for effective use; it’s not a point-and-shoot shotgun like a stocked model. For a more traditional setup, see our stocked shotguns.
- Limited Effective Range: The bead sight and short barrel are optimized for very close distances. It’s not suited for patterning at 25+ yards. For longer-range shotgun work, browse our optic-ready shotguns.
- Blued Finish Maintenance: The blued finish, while classic, requires more diligent cleaning and oiling to prevent rust than modern polymer-coated or stainless options.
Who This Firearm Is For (And Who Should Look Elsewhere)
Buy the Mossberg 590 Shockwave 20 Gauge if: You’re a DIY firearm enthusiast who enjoys customizing a proven platform. You understand and are prepared to practice the specific shooting stance it requires. You want a highly compact, reliable firearm for home defense or property use where maneuverability is key. You appreciate the reduced recoil of a 20-gauge for practical training. You’re looking for a Mossberg with serious build quality without the NFA paperwork.
Skip the Mossberg 590 Shockwave 20 Gauge if: You want a traditional shotgun you can simply shoulder and fire. Your primary use is hunting or clay sports. You’re unwilling to invest time in learning proper grip and firing technique for a pistol-grip shotgun. You require a firearm with a high magazine capacity out of the box. You operate in highly corrosive environments and prefer a stainless or marine-grade finish.
| Specification | Detail |
|---|---|
| Product Type | Non-NFA Firearm (Pump Action Shotgun) |
| Material (Receiver) | Solid Aluminum Alloy |
| Material (Barrel) | Steel |
| Manufacturing | Mossberg & Sons |
| Finish | Blued |
| Hardness/Quality | Military-Spec (Mil-Spec 3443E) Steel Components |
| Compatibility | Mossberg 500/590 Series Aftermarket Parts (20-Gauge Specific) |
| Installation/Usage | Manual Pump Action, 3″ Chamber |
| Weight (Unloaded) | Approx. 5.25 lbs |
| Dimensions (LxHxW) | 26.37″ x 5.5″ x 1.75″ (Overall) |
| Country of Origin | United States |
| Condition | New in Factory Box |
| SKU | MSS-590S-20G (Miamishooterssupply) |
| Feature | Mossberg 590 Shockwave 20 Gauge | Generic “Tactical” Pump (e.g., Hawk/Charles Daly) | Remington 870 Tac-14 (12 Gauge) |
|---|---|---|---|
| Material & Build | Solid aluminum receiver, mil-spec steel | Often cast/pot metal components, thinner steel | Steel receiver, good build quality |
| Quality & Durability | Proven 590 system, dual action bars | Inconsistent QC, single action bar prone to binding | Proven 870 system, but post-bankruptcy QC varies |
| Compatibility | Vast 500/590 20ga aftermarket | Limited to no aftermarket support | Good 870 aftermarket, but 12ga only here |
| Shipping & Compliance | Ready to ship, non-NFA status clear | May have compliance questions on import | Ready to ship, non-NFA |
| Lifespan/Durability | Designed for high round count, service life | Suitable for light use, not sustained firing | Good durability, but finish may be less robust |
| Price Point | $239.99 (Sale) / $299.99 (Reg.) | ~$180 – $220 | ~$350 – $400 |
Frequently Asked Questions
Is the Mossberg 590 Shockwave 20 Gauge considered a shotgun or a firearm?
It is federally classified as a “Firearm,” not a “Short-Barreled Shotgun” (SBS), due to its overall length exceeding 26 inches and its lack of a shoulder stock. It can be transferred to eligible individuals without an NFA tax stamp. Always verify your state and local laws, as some jurisdictions have additional restrictions.
Can I add a shoulder stock to the Shockwave?
Adding a shoulder stock to a factory Shockwave would create an NFA-regulated Short-Barreled Shotgun (SBS), requiring a tax stamp and registration. The platform is designed to be used with its proprietary grip or a stabilizing brace (in compliant configurations). For a stocked Mossberg, consider a standard 500 or 590 model.
How does the 20-gauge recoil compare to the 12-gauge Shockwave?
The difference is substantial. The 20-gauge generates significantly less felt recoil, making it much more controllable, especially during rapid follow-up shots. This makes the 20-gauge version an excellent choice for shooters sensitive to recoil or for those who plan on extensive practice sessions.
What is the effective range of this firearm with its short barrel?
With its 14.38-inch cylinder bore barrel and bead sight, it is most effective at very close ranges—think 7 to 15 yards. The short barrel causes shot to begin spreading quickly. It’s optimized for point-shooting in confined spaces, not for precision work at extended distances.
What kind of ammunition should I use in it?
It handles 2.75-inch and 3-inch 20-gauge shells. For defense, larger pellet buckshot (like #3 Buck) or a rifled slug is common. For practice, any standard target or field load works. We recommend testing several brands to see which cycles most reliably in your specific firearm.
Where can I buy the Mossberg 590 Shockwave 20 Gauge online?
You can purchase it right here from Miamishooterssupply (miamishooterssupply.com). We are an authorized retailer, and this unit is in stock, ready for same-day shipping from our warehouse in Boise, ID, following all federal and state regulations.
Is the Mossberg 590 Shockwave a good home defense firearm?
Its compact size, reliability, and potent close-range stopping power make it a viable option for home defense. However, its effectiveness is entirely dependent on the user’s proficiency with the unique pistol-grip platform and their understanding of shotgun ballistics in a home environment. Training is non-negotiable.
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About this review: This assessment is based on hands-on handling, technical specifications, and industry knowledge of the Mossberg platform. It is written for informational purposes to help qualified buyers make an informed purchase. All transactions are subject to applicable federal, state, and local laws.
Last updated: March 2026
