Piston Alignment

Piston alignment is rarely discussed and almost always wrong on a customer-walk-in AEG. With more than 2 AOE washers stacked under the head, the head can sit off-axis to the piston body, which produces FPS loss, premature mechanical engagement (PME), accelerated rack wear, and an ugly-sounding cycle. The alignment check below adds five minutes to the build and eliminates all four failure modes.

• Loctite Blue
• Small Phillips screwdriver
• Piston
• Real Deal High Speed Piston Head
• AOE washers (avoid sorbothane on this build — see chapter 5)
• The bonded gearbox shell

Do this step after the bushings have had at least 15 hours to cure.

1. Remove the screw and the bearing assembly from the piston head with the small Phillips driver.
2. Slide the screw back up through the piston and stack the 2–3 AOE washers around the screw shank.
3. Add one small drop of Loctite Blue to the screw threads.
4. Thread the piston head onto the piston body — snug, but not fully tight. You need it loose enough to adjust angularly.
5. Drop the (greased) cylinder over the piston and slide the whole assembly into the gearbox shell.
6. Look through the spring-guide bore. The piston should slide forward and backward smoothly under finger pressure. If it binds, rotate the piston head a few degrees and retest. Repeat until it slides freely.
7. Once the alignment is correct, hold the piston steady and snug the head down firmly. Let the Loctite cure undisturbed.

Note on the Real Deal Ultimate Performance piston: the body is already 3mm longer than TM spec, so it ships pre-AOE-corrected. With this piston you should not add AOE washers — the alignment procedure above still applies, but with zero washers in the stack. See chapter 5 for the full AOE discussion.