Airsoft Canada - View Single Post - M4 BBs not feeding, unless mag held in (update mar 15, resolved)

m102404 · March 11th, 2011, 09:19

It litterally doesn't take much on some setups to get it to feed/misfeed. Something as simple as overtightening the stock screw can pull the mechbox and other bits out of alignment.

Since the mag is held "stationary" in the lower receiver and the hopup is in the upper receiver those two parts can be out of spec. Add in variations with brands of hopups...and mags...and mag catches and any tolerance variations can stack up and result in less than ideal functioning.

1. You've narrowed down on what part needs to interact with the other for propper feeding of BBs up into the hopup...the tip of the feed tube needs to insert into the mag enough to set the BBs free so they can be sprung up into the hopup...and then be fire, etc...

You can try to address issue a couple of ways and certainly a list of things to check:
1. See that your mags are seating high enough....take the mag catch out and hold the mag up until the top of the cutout in the side of the mag matches up with the top of the slot for the mag catch. If it feeds like that then look to see if the top of the mag catch is actually high enough and doesn't have a lot of up and down play....several are undersized and have enough play to allow the mag to move up and down.

2. Insert a full mag up all the way...hold it up and shoot. If it feeds properly....then let it go...does it stop spitting out BBs after the next shot? If that's the case then the mag is riding too LOW (not forward or backwards). How much do you need to push it up (gradually) until you hear the BBs release and it starts shooting again (you can hear the BBs feed if you do it slowly/carefully enough). If it's just a little...then I'd suggest you shave the retaining catch on all your mags (note some mags have really long retaining catches...KA is notorious for it....others don't). Just remove enough to so that the mags continue to feed even if you're pulling down on them.

So...all it might take is a reassembly and not overtightening things. If you've got a lot of up/down play in the mag catch, try another one (nothing might work if you've got a lousy Dboys body). You might need to trim the BB catch (there's pictures and other threads on that...search for King Arms M4 mags not feeding or something like that)

Best of luck.

March 11th, 2011, 09:19	#7
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	It litterally doesn't take much on some setups to get it to feed/misfeed. Something as simple as overtightening the stock screw can pull the mechbox and other bits out of alignment. Since the mag is held "stationary" in the lower receiver and the hopup is in the upper receiver those two parts can be out of spec. Add in variations with brands of hopups...and mags...and mag catches and any tolerance variations can stack up and result in less than ideal functioning. 1. You've narrowed down on what part needs to interact with the other for propper feeding of BBs up into the hopup...the tip of the feed tube needs to insert into the mag enough to set the BBs free so they can be sprung up into the hopup...and then be fire, etc... You can try to address issue a couple of ways and certainly a list of things to check: 1. See that your mags are seating high enough....take the mag catch out and hold the mag up until the top of the cutout in the side of the mag matches up with the top of the slot for the mag catch. If it feeds like that then look to see if the top of the mag catch is actually high enough and doesn't have a lot of up and down play....several are undersized and have enough play to allow the mag to move up and down. 2. Insert a full mag up all the way...hold it up and shoot. If it feeds properly....then let it go...does it stop spitting out BBs after the next shot? If that's the case then the mag is riding too LOW (not forward or backwards). How much do you need to push it up (gradually) until you hear the BBs release and it starts shooting again (you can hear the BBs feed if you do it slowly/carefully enough). If it's just a little...then I'd suggest you shave the retaining catch on all your mags (note some mags have really long retaining catches...KA is notorious for it....others don't). Just remove enough to so that the mags continue to feed even if you're pulling down on them. So...all it might take is a reassembly and not overtightening things. If you've got a lot of up/down play in the mag catch, try another one (nothing might work if you've got a lousy Dboys body). You might need to trim the BB catch (there's pictures and other threads on that...search for King Arms M4 mags not feeding or something like that) Best of luck.