***IMPORTANT***: The M3D-AL was designed to use Glock Gen 4 internal parts, but still works with Gen 3/4/5 upper assemblies (Gen 3 recoil springs require installation of the included cap).
***IMPORTANT***: For the M3D-AL (Aluminum Pistol Frame), if you are using a Glock GEN 3 recoil spring, you MUST use the supplied conversion cap and place it front of the recoil spring (below the front of the barrel) when you insert your GEN 3 recoil spring into the upper assembly. Failure to do so will result in permanent damage to the frame. If you are using a GEN 4 or Gen 5 recoil spring, you do not need this cap.
***IMPORTANT***: We have applied a copper anti-seize to the friction points. This is NOT rust. Do not remove the copper anti-seize (apply more if needed).
***IMPORTANT***: When attaching an upper assembly (Slide, Barrel, Recoil Spring) to the M3D-AL frame, you must depress the trigger first to allow the upper assembly to move all the way towards the back to properly attach. Remember, if you are using a compatible Glock Gen 3 upper assembly, you must use the included cap that is placed in the front of the recoil spring (nearest the front of the barrel). The M3D-AL was designed to accept factory Glock upper assemblies and we cannot guarantee that all aftermarket slides will fit on the rail (as they may have tighter tolerances).