Guns Modify MIM 2 Stage Steel Hammer, for Tokyo Marui MWS M4/M16 GBBR

What this hammer changes. In a gas blowback rifle, the hammer is the component that strikes the valve to release gas into the chamber. A stock polymer or soft-metal hammer can deform over time, leading to inconsistent valve strike and erratic cycling. The Guns Modify MIM 2 Stage Steel Hammer replaces that with a CNC machined steel part designed to maintain its geometry through thousands of cycles.

The 2-stage design refers to the hammer's engagement profile within the trigger group. It provides a more defined trigger break and smoother reset compared to stock hammers, which can feel mushy or inconsistent as the gun accumulates rounds. This is not a full trigger group swap—it's a single component upgrade that tightens up the existing fire control assembly.

Build and fit. Machined from steel using metal injection molding (MIM), the part holds tight tolerances for reliable engagement with the sear and valve system. It drops directly into Tokyo Marui MWS M4 and M16 GBBR platforms without modification. If you're already running a Guns Modify MIM 2 Stage trigger system, this is the matching hammer. If you're upgrading from stock, it pairs with the existing trigger group to improve mechanical response.

Who this is for. Builders who have noticed their GBBR developing inconsistent trigger pull or cycling issues after heavy use. Also appropriate for anyone wanting to harden the fire control group before problems appear. This is not a velocity upgrade—it won't change FPS. It's about mechanical reliability and trigger feel.

What you need to know. Installation requires partial disassembly of the trigger group. If you're not comfortable working inside a GBBR receiver, have a tech handle it. Once installed, no break-in period is required—the steel surfaces mate immediately.