A compensator is intended to redirect the gas pressure wave that leaves the bore when a bullet is released from the barrel. This gas is then redirected (in most cases) upward to reduce muzzle rise and felt recoil.  Less felt recoil generally means less force is applied to cycle the slide, so a reduced force recoil spring is necessary. 

The Apex MRAT Compensator includes a guide rod assembly with a recoil spring pre-cut to a length that will work for most users.  If you find that your pistol doesn’t cycle properly with the MRAT and recoil assembly installed, you may need to trim the recoil spring incrementally until your pistol runs smoothly. 

Before you trim the Recoil Spring: 

  • Lubricate your pistol. 
    • Often, lack of lubrication is the cause of a malfunctioning pistol. 
    • For a guide to lubricating your pistol, see this link (this is based on striker-fired pistols, but the same lubrication philosophy applies). 
  • Assure that the compensator is not contacting your slide or frame while cycling.
    • First, unload your pistol and remove any ammunition from the area. Check to ensure you have it unloaded before you proceed.
    • Visually check there is a gap between the slide and compensator while the slide is in battery (fully closed). 
    • Lock the slide to the rear and check that the compensator’s spring box extension (the protrusion on the bottom of the comp) is not contacting the frame. 
      • If the comp is touching the slide or frame, you may need to readjust the compensator according to the installation video. 

Common malfunctions related to too little slide velocity: (remember, lubrication may be a cause of these too) 

  • Vertical stove pipe – Spent brass failing to eject and sticking straight up in the chamber area 
  • Linear stove pipe – Spent brass failing to eject and becoming lodged between the barrel hood and breech face. 
  • 3-point jams – A feeding malfunction where the fresh cartridge is trying to feed from the magazine into the chamber and winds up stopping the slide from going into battery.  Generally, the cartridge is contacting the breech face, top inside of the chamber, and the feed ramp. 

Trimming the Recoil Spring:

WEAR SAFETY GLASSES OR A MASK… Protect your eyes. 

Tools: Our springs are made from heat-treated, flat wire, spring steel, and we recommend using a rotary tool with a fiber-reinforced abrasive disc. 

How much to trim: Take approximately ¼ to ½ a coil off the open end of the spring, reassemble the pistol, and try shooting it again. In ideal circumstances, the spent brass should eject from your pistol and hit the ground between 2 and 6 feet away. 

Pro-Tip: Once you cut material off the recoil spring, you will not be able to put it back on, so use caution.