Ati Outdoors Alpha, Ati 15Ax410Kit18 Alpha 410 Upper Kit 18.5 5R Blk

The ATI Outdoors Alpha 410 upper kit transforms your AR-15 lower into a compact, versatile .410 shotgun. Built around an 18.5-inch smooth bore barrel, this upper assembly gives you a modern, modular platform for small-game hunting, pest control, and short-range shooting without needing to build an entirely new rifle. If you've already got an AR lower lying around—whether it's a standard mil-spec receiver from any manufacturer—you can convert it into a functional .410 shooter with this complete upper kit.

The Alpha kit includes everything you need to get running: a patent-pending polymer M-LOK rail system with quick-detach capability for accessories, an adjustable gas system with a knob for tuning performance, and a 5-round capacity. It ships with a cylinder-style choke and a 3-ounce buffer, so you're ready to load and test right away. The modular design means you can swap components or move the upper between lowers as your needs change, giving you flexibility that a fixed .410 shotgun can't match.

This is solid kit-gun territory: accurate enough for varmints and small upland game, handy in tight spaces, and a fun way to run .410 shells through the platform you already know how to run. The 18.5-inch barrel strikes a balance between handling and velocity, and the adjustable gas system lets you dial in the function to your specific ammo. Not a range-only plinker—a genuine working gun that happens to slot into your AR ecosystem.

Key Features

• 18.5-inch smooth bore barrel chambered in .410 bore
• Compatible with any mil-spec AR-15 lower receiver
• 5-round capacity
• Patent-pending polymer M-LOK rail with quick-detach points
• Adjustable gas system with manual knob for tuning
• Includes 3-ounce buffer and cylinder-style choke
• Modular upper-receiver design for flexibility and reconfiguration

Specifications

Frequently Asked Questions

Will this upper work on my AR-15 lower?

Yes. The ATI Alpha 410 upper is designed to mate with any standard mil-spec AR-15 lower receiver, regardless of brand. You don't need a special lower—any mil-spec receiver will function with this upper.

What comes in the box?

The kit includes the .410 upper assembly, a 3-ounce buffer, a cylinder-style choke, and the adjustable gas system. You'll need to pair it with a compatible AR-15 lower to have a complete firearm.

Can I adjust the gas system?

Yes. The upper features an adjustable gas system with a manual knob, allowing you to tune the action to your specific ammunition and preferences.

What's the barrel length and capacity?

The barrel is 18.5 inches of smooth bore, and the kit holds 5 rounds of .410 ammunition.