M4-Style Tactical Shotguns (ADA 4)

What is an M4-style shotgun?

“M4-style” or “M4-pattern” describes a semi-automatic tactical shotgun layout that the US military adopted in the late 1990s. The recognizable features are a receiver with an integral top rail and rear sight, a front sight post, a pistol-grip or collapsible stock, a tube magazine under the barrel and a barrel of about 47 cm (18.5″). Many manufacturers, especially in Türkiye, now build guns on this pattern.

The ADA 4 is our own gas-operated design in that style. It is not an AR-style gun. For AR-pattern magazine-fed shotguns (“AR-12”), see our magazine-fed shotguns.

How does the ADA 4 work?

The ADA 4 is gas-operated, meaning a small amount of propellant gas is tapped from the barrel to drive the reloading cycle.

1. The shell fires and the wad passes the gas port in the barrel.
2. Gas drives a piston system rearward, which pushes the bolt carrier back.
3. The bolt unlocks, extracts the empty hull and ejects it.
4. A new shell is released from the magazine tube onto the carrier.
5. The recoil spring returns the bolt, which chambers the shell and locks; the trigger must be released before the next shot.

Gas operation gives softer felt recoil than inertia or pump actions and is less affected by lights and optics mounted on the gun, which is why it suits duty shotguns. Read more about gas-operated semi-auto shotguns or compare systems in our gas vs inertia guide.

ADA 4 models and finishes

All nine versions share the same gas action, 76 mm (3″) chamber, 4140 steel barrel, aluminum receiver and Mobil-type chokes. Each is listed with 47, 51, 55, 61 and 71 cm barrels and capacities of 2+1, 3+1, 4+1, 5+1, 7+1 and 10+1.

Collapsible, fixed pistol-grip or walnut stock?

In some markets, collapsible stocks and pistol grips affect legal classification or importability, so a fixed or walnut stock may be the practical choice for civilian sales.

2+1 to 10+1 capacity and compliance variants

The ADA 4 is listed in six capacities so that one platform can meet very different rules.

• 2+1 for hunting rules and the UK Section 2 shotgun certificate (no more than two in the magazine, barrel at least 24 in).
• 3+1 to 5+1 for limits of five shells in the magazine, such as Canada’s cap on semi-auto shotgun magazines and Australia’s Category C threshold; 5+1 with an 18.5″ barrel is also the classic duty configuration.
• 7+1 and 10+1 extended magazines for law-enforcement, security and competition users where the law allows.

In Australia, self-loading shotguns are Category C (5 rounds or fewer, limited groups of license holders) or Category D. For Australian buyers who need a manually operated alternative with similar ergonomics, see our lever-release shotguns.

Choosing a barrel length

In the US, barrels must be at least 18 in (45.7 cm) and overall length at least 26 in to stay outside NFA short-barreled shotgun rules; all ADA 4 barrel options exceed 18 in.

Uses of M4-style shotguns

• Law enforcement patrol and response shotguns that pair buckshot and slugs with a red-dot sight and light.
• Private security site, transport and maritime security teams where shotguns are licensed for that role.
• Sport and 3-gun fast reloads from the tube, extended magazines and rails for optics.
• Home defense where legal for the owner, typically with a 47 to 51 cm barrel and a light.
• Hunting the walnut ADA4-04 and ADA4-09 with longer barrels and 2+1 capacity work as slug or field guns.

M4-style vs other tactical shotguns

Alternatives worth exploring include AR-style magazine-fed shotguns, pump action shotguns, inertia-driven shotguns and the full tactical shotgun range.

Shells, chokes and maintenance

The ADA 4 chambers 70 mm (2¾”) and 76 mm (3″) 12 gauge shells. Duty users typically choose buckshot and slugs with an improved-cylinder or cylinder choke; reduced-recoil loads should be function-tested in the exact configuration before issue. Clean the bore and bolt after each session, strip and clean the gas system every few hundred rounds or after wet or dusty use, keep the piston area nearly dry and lightly oil the bolt and rails. Agencies should keep a log of rounds fired and replace springs at the intervals their armorer specifies.

Legal and import notes

• United States imports need a licensed importer (FFL Type 08/11) and an ATF Form 6 permit, and the configuration must pass the “sporting purposes” importability test; features such as collapsible stocks and magazine capacity can affect importability, and semi-autos assembled with imported parts fall under 922(r). States such as California and New York add feature and magazine limits.
• Canada semi-auto shotgun magazines are limited to 5 shells; the RCMP classifies each model, and several models have been prohibited since 2020, so check before importing.
• United Kingdom Section 2 for 2+1 with barrels of 24 in or longer; otherwise Section 1.
• South Africa semi-auto shotguns are excluded from section 13 self-defense licenses; dedicated status under section 16 is the usual route.

We supply the configuration your importer or authority confirms and never advise on getting around local rules.

Private label and agency orders

The ADA 4 can be built under your brand, with your logo, finish colors, stock type, barrel length and capacity specified per order. Government and law-enforcement buyers can request evaluation samples, and we accept orders of any quantity. See private-label shotguns and how our shotguns are made.

Reviewed by the Iber Arms technical & export team, October 2026.