Magazines Not Catching

[AnthonyG]

Ive got a King Arms M4 that has problems with certain mags catching. It's not that the magwell needs tape or Velcro, I have that, and mags don't shake around at all. The issue seems to be that the mags don't insert far enough to catch at all. The one exception are my King Arms mags which I measured with my callipers, and they seem to have a marginally shorter distance between the top of the mag and the catch notch.

I foresee a few solutions, and I'd like some opinions. I could grind down the top of the mags to make them insert farther, or I could grind down the the bottom part of the gearbox that extends into the magwell.

Are there any other things I could try, or has anyone experienced similar problems?

[RainyEyes]

What are the brands of the magazines that do not catch?

[ox56]

Had that problem with my ics m16 when i got a new lower reciver but later on i found out the issue was the hopup placement does it have alot of play in the upper reciver while the gun is put together

[AnthonyG]

Originally Posted by RainyEyes

What are the brands of the magazines that do not catch?

MAG and VFC, all midcaps. The VFC has the longest distance between the top of the mag and the catch hole.

Since the mags are only fit via friction, the problematic mags will usually drop loose after a few rounds from gearbox vibration and the tension of the mag spring.

Now that I look at it again, It's hard to say which direction is problematic, whether its the up-down or forward-back.
One thing for sure is that the magazine release is sitting proud of the receiver which indicates it hasn't clicked in to place. With my King-Arms mags it sits flush.

Originally Posted by ox56

...does it have alot of play in the upper reciver while the gun is put together

Not really, I've always felt unlucky that that the tolerance on this particular receiver is a bit off since inserting my rear body pin is super-tight.

[Rossco66]

There are some issues that are recurrent. VFC e Series M4 and a Pro Win Hop up unit meant a bunch of magazines wouldn't catch in mine. Changed out the Pro Win and the problem disappeared.

[AnthonyG]

Well... my hopup is stock. Maybe Ill try removing the hopup and see how the mags catch.

[AnthonyG]

Problem isnt the hopup. Mags still wont catch with upper receiver removed.

[Cliffradical]

Have you tried the mags with your fitment mods removed?
My KA eats just about anything as long as it has plenty of room for slop (sounds backwards, I know). I've had problems feeding while my KA mags were weighted, and bullshit Pmags being bullshit Pmags, but that's about it.

[AnthonyG]

Took out the velcro strip at the back of the mag well.

Mags are catching much better. Still need a good solid tap on the butt to get em up in there.

Guess I'm spoiled by the mag well on my VFC...

[jordan7831]

Couldn't you simply take a needle file and file the hole where the mag catches locks into? Sounds like there mag catch hole isnt perfectly aligned with the catch itself.

Found this video:
https://www.youtube.com/watch?v=bSY8aDpt3UM

[AnthonyG]

Went to play today without the fitments. Magazine feeding was an absolute nightmare.

[Cliffradical]

I'm surprised that the MAG mags are giving you troubles. You're sure there's no hopup front-to- back fitment stuff? Is the outer barrel in the right spot for the false crown to hold the hopup unit properly?
There's got to be a funny small thing here, a KA should pretty much be grab and go.

Your mags are broken in and your tappet plate is resetting correctly, just to be sure?

Edit: I bring this up because every MAG mag I've used has been a solid buy, except that they've all needed to be worked in manually before they'll feed properly. This means hammering a full load in and back out again with a loading rod, wet usually, or more runs plus a cleaning afterward if you don't believe in lubing magazines.

[AnthonyG]

After testing several combinations of mags and velcro fitments on the inside of the magwell I ended up putting a small 1/4" strip of velcro inside the mag well on the opposite side of the mag release catch. The strip lines up with the large groove on the side of a standard STANAG magazine. No front-back Velcro or tape was necessary.

I found this limited side to side movement and kept my mags pressed firm and engaged with the magazine catch.

I still have difficulty with my VFC midcap (has taller distance from top of mag to mag catch slot), MAG mags feed the best. My King Arms mid caps feed well with .2g BBs, but once I move up to anything heavier feeding is hit and miss, but this is independent of the original problem.

[Cliffradical]

Cool, I'll go ahead and do that mod to mine. Thanks!