Arm Or Ally Duty Slide w/ RMR Cut For Glock 20 (10mm)

Arm Or Ally Duty Slide w/ RMR Cut For Glock 20 (10mm)

The Arm Or Ally Duty Slide w/ RMR Cut for Glock 20 provides a rugged, optic-ready foundation for full-size 10mm Gen 1–3 builds. Precision CNC machined in the USA from 17-4 stainless steel, this stripped slide combines a solid-body profile with direct-mount RMR compatibility and practical front and rear serrations.

The G20 platform places greater demands on an upper assembly than smaller-caliber configurations. This Duty Slide retains substantial material around the top and sidewalls rather than relying on large windows or aggressive lightening cuts. The result is a straightforward 10mm slide designed around strength, component compatibility, and a clean full-size profile.

Built for Full-Size 10mm Builds

Designed for Glock 20 Gen 1–3 dimensions, the slide accepts compatible 10mm barrels, recoil assemblies, internal components, and Glock-pattern sights. Its full-size geometry provides the foundation needed for replacing a factory upper or completing a custom large-frame build.

The closed-top design works with standard flush-and-crown barrels as well as compatible threaded Glock 20 barrels. Because the slide does not include a functional port window, it should not be paired with a barrel that requires exposed top ports to vent correctly.

Solid-Body Duty Profile

The Arm Or Ally G20 Duty Slide keeps its exterior machining deliberate. A closed top and uninterrupted sidewalls preserve the traditional large-frame slide profile while limiting the openings through which dust, fouling, and debris can enter the upper assembly.

This configuration is intended for builds that favor a substantial, conventional slide over windowed or competition-inspired designs. At approximately 10 ounces, it retains the solid feel expected from a full-size 10mm upper.

Direct-Milled RMR Optic Cut

The slide is machined with a Trijicon RMR-pattern optic cut, allowing compatible red dots to mount directly without an adapter plate. Compatible optics include the Trijicon RMR and SRO, Holosun 407C, 507C, and 508T, and other models confirmed to use the same RMR mounting interface.

The optic cut is positioned ahead of the rear sight dovetail, preserving space for compatible Glock-pattern iron sights. Sight height should be selected according to the optic body and the backup sight picture desired.

The Trijicon RMRcc and Holosun K-series use different footprints and do not mount directly to this slide. Confirm the optic footprint, mounting-screw length, thread engagement, and recommended torque before installation.

Front and Rear Angled Serrations

Deep angled serrations at the front and rear create defined gripping surfaces for loading, press checks, and malfunction clearance. The forward serrations provide a convenient manipulation point away from the optic, while the rear serrations retain a familiar gripping location.

The serration pattern adds functional control without covering the slide in decorative machining. Its restrained layout complements the solid-body profile and keeps the optic area uncluttered.

17-4 Stainless Steel Construction

Each Arm Or Ally G20 Duty Slide begins as American 17-4 stainless steel and is precision machined for compatible Gen 1–3 components. This material provides the strength and dimensional stability appropriate for a full-size 10mm slide while supporting detailed serrations, sight dovetails, and optic-cut geometry.

Machined surfaces and component interfaces are held to consistent dimensions to support proper assembly with correctly specified barrels, recoil systems, and internal slide parts. Final fit and function also depend on the dimensions and quality of the components used to complete the upper.

Custom Finish Options

The Arm Or Ally Duty Slide is available in a rotating selection of custom finishes, including subdued solid colors, camouflage treatments, metallic appearances, and specialty patterns. Depending on the selected variation, the slide may feature a QPQ Nitride or Cerakote finish for added surface protection and a distinct completed appearance.

Pattern placement can vary slightly on camouflage and specialty-coated slides. Review the selected variation and product images to confirm the intended color and design before ordering.

Stripped Glock 20 Slide

This product is sold as a stripped slide. It does not include a barrel, recoil spring assembly, internal slide components, iron sights, optic, optic cover plate, or mounting hardware unless the selected variation specifically states otherwise.

Completing the upper generally requires a Glock 20 Gen 1–3 barrel, compatible recoil spring assembly, firing pin assembly, firing pin safety and spring, extractor assembly, channel liner, back plate, and iron sights.

Arm Or Ally guarantees replacement fit and function on factory frames when the slide is assembled with a factory Glock slide completion kit or an Arm Or Ally Slide Completion Parts Kit. Fitment and operation with other aftermarket components may vary.

Glock 20 Gen 1–3 Compatibility

The Arm Or Ally Duty Slide is designed for Glock 20 Gen 1–3 pistols and compatible large-frame Gen 3-pattern builds chambered in 10mm Auto. The slide must be completed with G20-compatible components rather than parts intended for standard-width 9mm platforms.

This slide is not a direct replacement for Glock 20 Gen 4 or Gen 5 pistols. Differences in recoil assemblies, slide geometry, frame interfaces, and generation-specific components prevent universal interchangeability.

Features

• Designed for Glock 20 Gen 1–3 pistols and compatible large-frame builds
• 10mm Auto slide configuration
• Precision CNC machined from American 17-4 stainless steel
• Solid-body profile without top windows or functional barrel ports
• Direct-milled Trijicon RMR optic footprint
• Compatible with Trijicon RMR and SRO optics
• Compatible with Holosun 407C, 507C, and 508T optics
• Front and rear angled serrations
• Accepts compatible Glock-pattern iron sights
• Compatible with standard and threaded Glock 20 Gen 1–3 barrels
• Uses compatible Glock 20 Gen 1–3 internal slide components
• Available in QPQ Nitride and Cerakote finish options
• Stripped slide configuration
• Made in the USA
• Approximate weight: 10 oz.