Picked up a G&P Magpul M4 with a locked up gearbox/trigger and missing stock and stock tube. Snagged it for 50 quid!
Completely stock but with Magpul receiver, Pistol grip, handguard and foregrip.
Cracked it open, seems that the cocking lever spring has been overstretched so the bolt cover won't spring back as it should.
In the gearbox I found the spur gear shaft completely sheared off and the motor pinion well worn. Replaced the spur gear, Air seal was OK, but I switched out the full cylinder for a 4/5ths as well as a new piston and cylinder head (which had to be modified to fit the gearbox protrusions)
Seems to be working OK if a little bit tight sounding. Going to grab some parts from AK2M4 to get her really purring, as well as a stock tube and stock. The intention is to have a full set of M4A1 and Magpul furniture to switch between.