MP5 stuck in full auto

[Cerwin]

Howdy

My TM MP5SD5 is well used and was upgraded by the previous owner with tight bore, PDI 150% spring, and various metal body parts.


When the gun is in semi auto it continues to cycle acting like full auto. Occasionally it will only cycle 2 or 3 times and then stop, but for the most part it will empty the entire magazine.

When the gun is dry fired it works flawlessly. It only cycles once with 1 pull of the trigger. When the gun is not loaded and dry fired it has never cycled more than once. But when it is loaded it just keeps firing.

I had the gun torn down to inspect for worn or broken parts. The selector plate is slightly worn but the selector switch seems to operate it without a problem I don’t believe that the selector plate is the problem. I did not open up the mechbox at all so I’m not sure the condition of the internals.

Other than this problem the gun fires flawlessly

Any comments or direction will be greatly appreciated thank you in advance for your time and help.

[CDN_Stalker]

Lower grip got put on in full auto mode. Needs to be in semi when you slide the grip on. At least that is what happend to mine at one point. Another occasion, an M733 that I had to try to fix the full in semi shooting, never got rectified until a new mechbox got put in. Luckily, the owner of the M733 (Apocolypse) had no idea WTF semi was for anyways. :lol:

[TheYellowDart]

Is the spring between the selector plate and cut-off lever missing or busted?

[Cerwin]

No the spring and the lil leaver the spring attaches too on the other side of the selector plate seems to be working just fine.

The spring does look a lil worn and out of shap but still pushes the pin back

Is it posible to purchase a complete replacement mechbox?

[globalogicom]

Did you every find a solution? I have same problem.

I have an A4 S-System by A&K. It is fairly new, less than 10,000 bb.

When the gun in in auto in continues to cycle in full auto even if I depress the trigger, sometimes it stops after a 5 seconds sometime not until the mag emptied or I drop the mag.

When the gun is in semi auto it normally does ok, but sometime continues to cycle acting like full auto. Occasionally it will only cycle a couple times and then stop, but usually it will empty the entire magazine.

When the gun is dry fired it works fine in both semi and auto. It only cycles once with 1 pull of the trigger. But when it is loaded it just keeps firing.

I even tried using different mags, but same problem.