In this guide, we will explain the mounting details of the Surefire X300U pistol light so you can be sure it is compatible with your handgun.
There are various standards for pistol light mounting, so it is important to know which pistol light is compatible with the handgun you want to use it with.
We will cover what to look for on your handgun and the specifics for mounting the Surefire X300U pistol light.
Handgun Requirements for Mounting a Pistol Light
Most full-size handguns come with one of two light rails underneath the barrel just in front of the trigger guard that is just under one inch wide. The light rail will have one or more cross slots that locates the light on the pistol and prevents it from moving during recoil. The light will also typically have a clamping rail that secures it to the pistol.
The first type is the “GL Standard”, “Glock Universal”, or just “Universal” light rail. This light rail has a single cross slot that is about 4mm (5/32”) wide. Glock handguns will have this light rail along with other brands of handguns.
The second is the 1913 rail or Military Standard “Picatinny” rail. This rail will have multiple slots that are about 5.2mm (3/16”) wide.
The photo below shows a Glock Universal light rail on the left and a 1913 light rail on the right.
Compact carry handguns like the Sig Sauer P365 and Springfield Hellcat have different mounting requirements since their mounting rail is smaller, around 0.8 inches wide. These pistols do not have a set standard, and pistol lights often need to be purchased for the specific handgun. Some do not have light rails at all.
Mounting the Surefire X300U Pistol Light
The Surefire X300U pistol light was designed to be used on full size frame handguns like the Glock 17/19, Sig P320, and the Walther PDP. It is too large to be used on compact carry handguns like the Sig Sauer P365 and the Springfield Hellcat.
The mounting system for this light includes two different methods, the “Lever Latch” system and the “Rail-Lock” system. The Lever Latch system can be easily taken on and off the handgun by pressing down on the side tabs. The Rail-Lock system is more robust and includes a key that slides into place and lock actuator screw that locks the light onto the pistol.
Each system includes two keys, one for the Universal standard and one for the 1913 standard.
The photo below shows all of the mounting hardware that is included, with the Lever Latch system installed for a Universal light rail.
For the Lever Latch system, two levers are included that are marked “U” for universal and “P” for 1913 Picatinny rail. The rails on the light must be removed to change out the levers.
For the Rail-Lock system, two keys are included that are marked “U” and “P” as well. Similarly, the rails on the light must be removed to change out the keys.
After selecting the mounting system and light rail key, the light can be mounted to the handgun. For the Lever Latch system, simply pull down on the tabs and slide it in place as shown below.
For the Lever-Lock system, pull the tabs to the rear of the light and pull the key out of the light rail.
Install the light on the pistol and push the key back into position until it snaps closed. Finally, tighten the lock actuator screw snug, but do not overtighten.
Will the Surefire X300U Fit your Pistol?
The Surefire X300U will fit any full-size pistol that has a Glock universal light rail or a 1913 light rail. Almost all full-size handguns have one of these light rails. This pistol light will not work with compact carry handguns like the Sig P365 and Springfield Hellcat.