Headless-Screw AEG Nozzle Alignment

Nozzle/Barrel Alignment

If you’ve worked on AEG’s, you’ll likely have encountered alignment issues between the inner barrel and the nozzle. This misalignment can cause the nozzle to drag along the hop-up chamber, creating unnecessary wear, reducing feeding reliability, and potentially issues with compression!

An easy way to check alignment is to remove the hopup chamber, then install just the gearbox and inner barrel. Assuming there is little play in the inner/outer barrel, this should give you a good indication of the alignment of the two parts! In this case, the gearbox does not line up with the inner barrel and will need an adjustment installed!

This is a before and after comparison showing a misaligned nozzle and inner barrel viewed from below next to a correctly aligned nozzle and gearbox, also viewed from below. The before image is prior to installing a headless screw (also known as all-thread), while the after is the result of correct adjustment.
With the headless screw cut to length a nut is also needed to tighten down the gearbox shell. A brass standoff is a good choice as it can easily be cut and modified to fit.

By using a matched-length headless screw (all-thread) you can have a rigid adjustment that lets you set the left-right alignment of many types of gearboxes in addition to a bit of extra rigidity in the receiver as the screw acts as a brace between the two halves.

You'll Need:

  • A headless screw (M3 all-thread) with enough length to cut to the width of the receiver.
    • A long regular screw can be cut and used as well!
  • A nut to secure the screw that will fit between the receiver and gearbox.
    • Brass-standoffs work well as they can be easily cut and shaped.
  • Locktite to secure the screw in the threaded half of the gearbox to hold the adjustment during service disassembly.

Start by:

  1. Measuring the width of the receiver where the screw will sit, cut/grind it to length, and then polish the ends to reduce scratching and scraping.
This is a correctly cut headless screw fitted snugly in the receiver of an AEG airsoft replica. Polishing the ends is recommended to minimize scraping.
  1. Install the screw into the gearbox with the nut to tighten it down, then fit the shell into the receiver to check initial alignment.
    1. Calipers can save time by measuring the width of the receiver and gearbox, then splitting the difference to center the screw.
The headless screw and nut are installed in the front screw hole of the gearbox. It can be turned in and out to shift the gearbox position in the receiver left or right.
  1. Remove the gearbox and turn the screw in/out to adjust where the gearbox sits in the receiver.
The gearbox is installed in the lower receiver to check fit and alignment. A well-cut screw should be snug and the gearbox should be set into position to check alignment with the nozzle.
  1. When you have the adjustment correct, a bit of locktite will hold the screw in place when removing the nut for servicing, then do a final install and check of the nozzle alignment.
There are two screws installed in this gearbox; one in front and one at the rear. Both are adjusted to center the gearbox in the lower receiver and align the nozzle with the inner barrel.

If you did it correctly, the gearbox should naturally fit snugly in the receiver and have perfect left/right alignment with the inner barrel of the gun!