I have had my MAG brand midcaps for about 6 months now, and never had any problems until last night when I noticed they were not feeding correctly, only every other shot fired a bb. On further inspection I realized the bbs were staggered. I also could not release the bbs. I tried using silicon oil and taking the spring out and re feeding it. No luck. All of my mags just all of a sudden did it. The problem was most likely my overfeeding of the mags. This also happened with my plastic Pmag and even the new metal midcap I got in the mail the same day. I can even release the bbs from the new midcap when I pull the bb release button. Any ideas? I've never had this problem before and I know it is my mags as I tried my friend's midcap and hicap and they worked. It just seems peculiar for every mag I own to go bad on the same day when they are numerous brands.
Your mags may need to be disassembled and cleaned. Lubing them is controversial because the lube will get into the hop up, which is undeniably undesirable. The loading system for mags is actually not 100% perfect and the follower can be modded to feed bb's more reliably in a double stack configuration.
Anything is better than an oil/petroleum based lubricant. Petroleum and its derivatives have a nasty habit of eating rubber. As it turns out, there are some very important rubber parts in airsoft guns, including the hop up bucking, which your bbs will pass right through.
I've never used graphite lubricant in airsoft, so I'm speculating entirely here, but I wouldn't want to use a powder anywhere in my gun. You've already got liquid lubricants and adding a solid to the mix is going to gunk things up. Stick with 100% pure silicone oil for a tried and true lubricant. Generally, you want something between 10 and 20 weight for best results in pretty much all non-gearbox applications:
Whatever the capacity of that magazine is, put in half and you will not have any problems of jamming. The most common issue with mags is that people try to cram every single bb that the mag can possibly hold and it almost always leads to the very problem that you have.
I've got at least 10 mags ranging from 30 rounds to 120 rounds or more and I never put more than 30 bbs in any of them and I don't run into any jamming or feeding issues.
EDIT: just noticed this was an epic necropost. Hopefully my post will still be of use to someone.
Last Edit: Sept 7, 2012 9:30:36 GMT -5 by M.S.-ARC
I've never used graphite lubricant in airsoft, so I'm speculating entirely here, but I wouldn't want to use a powder anywhere in my gun. You've already got liquid lubricants and adding a solid to the mix is going to gunk things up. Stick with 100% pure silicone oil for a tried and true lubricant.
Maybe I'm using it wrong, but I've never had good luck with any kind of silicone lube. I've always been a fan of the graphite powder, as it won't gum anything up the way oils will, an it lasts forever. Now granted, it's a bit on the messy side when applying it, but I have yet to see any adverse effects to any gun I've loaded the mags into (I never use the powder on the gun internals themselves, just along the magazine feeding tube- gonna throw that little disclaimer there so someone doesn't try to lube up their gears with graphite powder and blame me for it).
Edit- Just re-read the OP's post, unless you clean the bajesus out of the mags so that none of the old oily stuff is in there, I seriously recommend going with Knief's suggestion. Not sure how the powder would react to the oils, and probably safer to just not do it
In general, you shouldn't need much lube in your magazine anyway. If your follower is jamming up in newer mags, you might just need to break the mag in a bit. After that, unless they get dirty and you need to clean them out, you shouldn't really need to lube your mags.