Potential Defect with Stock TM MP7 Cylinder Head

[Colin_S]

Hey guys I'm just posting this up so MP7 users are aware of a potential defect with the stock TM MP7 cylinder head. In the last month I've worked on two TM MP7s (both stock), one had a jammed mechbox while the other operated with no issues.

Anyway on both occasions after I disassembled the gun I noticed chunks of rubber broken off the cylinder head damper pad (dunno if that's what it's called). Again on both occasions the rubber bits were then pushed up elsewhere against the rubber pad which caused an uneven striking surface.

This caused one of the MP7s to break its piston head (about 1/4 of the plastic head broke apart into pieces) while with the second MP7's piston head developed a large crack on the surface. Unfortunately I don't have pictures of this part because I'm an idiot and threw out the piston head without thinking.

Attached is a picture of the cylinder head and the rubber pieces, the damage on both MP7s was in the same location. I'd love to hear what other MP7 users have experienced when working on the mechbox.

I hope this helps those of you who have experienced failures with the TM MP7.

[nic_s]

Very interesting. Here's what I noticed with mine. The spacing between the piston head and piston is not enough, so the sector gear will try to engage the piston while it is too far forward. This has resulted in my gun chewing through the first tooth of both the stock and a poly piston. I've heard that proper spacing with washers can fix this problem. My cylinder head looked just like that - it didn't fire right out of the box.

[ThunderCactus]

Seen that too, but after about 50 mags of use. Piston head cracked due to striking the rubber un-evenly. Upgrade parts fix that easily