As usual I never leave well enough alone and took apart the CA M15A4 CQB today. CA certainly did a better job with this gun than with the MG36. Anyway taking the gun apart is as easy as removing the front body pin, the top receiver slides right off.

Removing the mechbox from the lower receiver just exactly the same as any metal M4/M16. The mechbox shell is reinforced by default and the metal is much harder than the flimsy stuff that TM uses. The mechbox uses 7mm bearing bushings so if you want to use a high tension spring, you’ll need to replace them with regular metal bushings.

After opening the mechbox I found that CA equips the M15A4 CQB with a metal ball bearing spring guide, reinforced metal gears, a metal cylinder head and an aluminum ball bearing piston head. I was surprised to see CA equip the gun with an aluminum piston head since aluminum piston heads are suppose crack the mechbox quicker than plastic versions. Oh well I know CA reinforced version 2 mechboxes are quite sturdy so we’ll see how long this thing lasts.

The entire mechbox is lubricated well however CA uses gear grease on the piston/piston head too. The grease has a lower viscosity than the stuff TM or Systema use however you can still feel the resistance when moving the piston inside the cylinder. I cleaned out the piston, piston head, cylinder and cylinder head and applied some silicon oil for smoother movement.

The only surprise I ran into was the amount of wear on the teeth on the plastic piston. Stephen took excellent care of the gun and I fired less than 200 rounds total yet the entire first tooth and half of the second tooth was worn down! Talking previously to Carl at ASCA about CA pistons, he mentioned that CA may have a problem with timing between the gears and piston. When you line up a CA piston with a TM or a Guarder polycarbonate (which copies TM), you see that the CA spacing between the teeth is slightly farther apart.

You can see in the second picture the shards of plastic that I was able to remove from the piston tooth gap. The piston has been replaced with a Guarder polycarbonate and I’ll open up the gun next month to check on the wear…

I also replaced the spring with a Guarder SP100 however because the CA M15A4 CQB uses a M4 cylinder and has a short inner barrel, muzzle velocity only increased ~10 fps. 🙁 Oh well I planned to replace the outer barrel with something longer and add a longer tightbore inner barrel as well so this won’t be much of an issue.

Overall I love the CA M15A4 CQB! 😀 The rifle is so solid and small enough that I can run and gun. It may have CQB in its name but I plan on using it in the field on the 27th when Mark and I hit up FlagRaiders. A field game will allow me to get comfortable with the gun and I can write a more detailed review then.