King Arms M4 Feeding Problems + Ammo Problems

[AnthonyG]

So.

I still haven't been able to fix the problem fully. I reinstalled the original nozzle, and took the recommendation of putting Velcro in the back of the mag well as opposed to the front where I had it before.

My King Arms seems to shoot fine with the King Arms high-cap that came with my gun (no miss-fires, and consistent FPS), but I'm continuing to have problems with most of my mid-caps (mix of King Arms and MAG brand).

Is it possible that it's an issue related to the spring tension inside the mag. Are the mid-cap springs too weak to move BBs up into the hop up chamber? Is this perhaps a problem with the hop-up unit? Have the offending mid-caps reached the end of their life?

I was playing today and noticed a similar problem with my mid-caps on my VFC scar. With the VFC the problem is not as severe; it miss-fires every 5th BB or so. The same mag in the King Arms will fire the first shot, but none after that.

[RainyEyes]

Originally Posted by AnthonyG

So.

I still haven't been able to fix the problem fully. I reinstalled the original nozzle, and took the recommendation of putting Velcro in the back of the mag well as opposed to the front where I had it before.

My King Arms seems to shoot fine with the King Arms high-cap that came with my gun (no miss-fires, and consistent FPS), but I'm continuing to have problems with most of my mid-caps (mix of King Arms and MAG brand).

Is it possible that it's an issue related to the spring tension inside the mag. Are the mid-cap springs too weak to move BBs up into the hop up chamber? Is this perhaps a problem with the hop-up unit? Have the offending mid-caps reached the end of their life?

I was playing today and noticed a similar problem with my mid-caps on my VFC scar. With the VFC the problem is not as severe; it miss-fires every 5th BB or so. The same mag in the King Arms will fire the first shot, but none after that.

Spring tension deficiencies are usually more prone in high-caps rather than mid-caps. I've yet to have feeding problems with midcaps on either m4 or g36 series magazines.

Since it's happening with every KA magazine I doubt it's the magazines since it's highly improbable that they all reached a point of failure, but if you've done some nasty stuff with your mags I wouldn't be surprised.

This could be a side issue: what brand of bb's are you using? I've heard feeding issues with systema magazines and certain brands.

The hop-op could be an issue. Depending on if the plastic that forms the hole that makes contact with the magazine pushes the stopper sufficiently. You said you added a velcro to the back which should have stabilized and fixed that issue.

Make sure that the hopup chamber makes sufficient contact with the stopper. Due to the tolerances of my jg g36 had feeding issues with cyma magazines that were alleviated when I filed off some of the shell. They're still hard to insert (hop up chamber and bb hole don't fit 100%), I have to push them in hard, but they still feed flawlessly. That could be the case for your KA M4 but it's kinda stupid how the magazines made from the same company as your gun might not be compatible.

[AnthonyG]

BB Bastard 0.28 Bios is what I'm using

The KA hop up unit is metal and the only thing I've done is changed for a flat hop. When I look down the barrel its not like there is anything protruding that might stop the BBs from being fired, plus changing the hop up rubber is a relatively simple process

I mean Id hate to be at a game, borrow a friends mag only to find it doesn't work because of some tolerance issue in my gun.

I'll check how the mags are sitting in the hop unit

[RainyEyes]

Originally Posted by AnthonyG

BB Bastard 0.28 Bios is what I'm using

Some brands of bio bb's actually do have feeding issues, and I do believe BB bastards is one of those brands. Hopefully someone else can chime in on this revelation.

http://www.airsoftcanada.com/showthread.php?t=167135

[AnthonyG]

Hmmm. I'll try my non bios this weekend see what happens.
This sucks because I just got the case of 10K 0.28s

[AnthonyG]

I just completed a bunch of testing using various ammo and magazine combinations. The only other type of ammo I had access to was Valken 0.25s non-bio. The BB Bastard Frag ammo seems to be problematic from what I can tell, and my King Arms mid caps seem to be the worst performers. I'm kind of upset because the sales rep (at Hero's) who sold them to me implied they were the same as the regular BB Bastard ammo, which they clearly are not. I definitely won't be buying Bastards any more, there wasn't a scenario I could come up with where there wasn't at least a minor problem)

Also, my MAG brand magazines don't seem to sit well in my magwell. After about 5 shots the magazine's spring trys to push more BB's into the hop-up, but instead pushes itself down and out of the magwell about 1/4" which prevents and more BB's from feeding.

Here is a chart I made that summarizes my findings. Red is the worst, with no feeding possible in all but the most forced scenarios. Green is no problems, or what I would consider perfect, light-green is "usable" but with minor problems. Yellow is frustrating and inconsistent feeding.

Some magazines have #s which correspond to a labelling system I have on these mags to keep track of which ones I'm using in-game.

[RainyEyes]

Looks like the bb's were a contributor but not the causal factor. I would still try to modify the mags to sit better in the magwell/receiver. Duct tape usually works, just to keep it in place and prevent wobble.

[AnthonyG]

There were definitely multiple factors at play; before I fixed my nozzle I was getting mis-feeds and double feeding in all of the "green" scenarios above.

Now I've narrowed it down to a game of mag type + ammo type.

The mags are pretty sturdy (almost no wobble) with the velcro mod, and it's only the MAG brand mags that are "un-seating" themselves. I suspect this is a problem with the mag release and the location of the notch in the side of the MAG mags where they are held in place.

Edit: This thread has taken a turn since the problem isn't my gun any more.
I might post my chart as a separate thread, or post in another thread dealing with ammo/mag problems.