G&P gearbox cylinder
 

I have a G&P M4 RAS II short and I ordered new front set for it along with a 509mm inner barrel. my question is how i can tell which cylinder i have in my gearbox? i don't see holes, rings ..etc.

If it doesnt have any holes then it's a full cylinder.

Strange that was in a CQB gun though....unless it's not stock parts.

Theres a possibility the port could have been rotated to face down.
Its not uncommon although its not common either...lets just say it happens sometimes.

Unfortunately the only real way to know for sure would be to take it apart.

Try rotating the cylinder in side the gearbox. You may be lucky and you can see a port. I was told by some HK friends that G&P no longer puts ported cylinders on their new guns.

I can't seem to turn the cylinder. Could it be a tapered cylinder? i bought the gun 3 years ago. How hard is it to swap out the cylinder? I have never taken a gearbox apart coz I am afraid something pops out and i can't put it back together. anything to align/adjust after a cylinder job? like motor to gearbox?