agm m4 mag problem / quick fix

[johnnyj]

ok today my little lad fired my m4 upside down ( mag was gassed but not loaded ) the gun half fired and vented the gas in the mag

i came to refill the mag and found it would not hold gas any longer as it was venting from the out let valve i was going to bin it but decided to see what the problem was and this is a quick take down guide of how i did it :

tools you need are :

allen key set
roll pin punch
fine pin punch
pliers
knocking stick
gas gun lube


To start remove the 4 small pin that are on the side/front of the mag these hold the feed spring cover

after taking the cover off remove the spring and plastic bit from the top

next job is to remove the top cover with the feed lips and and what not very simple to do as its just 2 allen nuts holding it on , after the nuts are removed it will pull away very easy back first

the next thing to come out are a roll pin thats at the rear of the mag , there are only 2 and your taking out the top pin

now that has been removed there is one last pin to be taken out and this is the top pin at the front of the mag

the top half of the mag will now pull free BUT take care on the right hand side of the block there is a small spring that would be very easy to lose , there should be 2 plastic arms for the bolt lock and 1 metal arm for the valve reset

now just remove the valve from the rear of the block turning ccw , i used a pair of pliers for this but its not tight

on taking out the valve i could see the problem , the O ring at the back of the valve had become unseated at the same i noticed it was dry as hell i reseated it and gave it a good soaking in some gbb spray

refitted all the parts in reverse and now works a treat with no leaks , after doing all this i found out its a very common problem with the agm mags so i dont know how long it will last but its only a 10 min job to reset

hope this help some one