TM M4 not firing
 

Sorry for such a simple question, just looking to diagnose my AEG before I finalise a sale.

If I pull the trigger and I get a 'klunk' sound, what exactly does that mean? (I'm not sure of the battery's charge)

Ok, if there's no BB jamed in there then it most likly the gears/mechbox.

Cupple questions for you.

Is your m4 upgraded? If so with what?
What size batery?
How old and how used is this gun?
Have you opend it to see if you could find any problems?

charge your battery!!!

You might also want to check your hop up, while your at it.