King Arms M4A1 feeding issue
 

Hey everyone!

I have this brand new M4A1 from KingArms with a little problem...

When fired on full auto the first bb that comes out is at 400fps, the next tree bbs just roll out of the barrel.

Checked the gearbox, the airseal is allright
Inner barrel and hop up seems fine to me

Tried different brands of magazines like Magpul Pmags, G&P, G&G, MAG, SRC, but it doesnt change a thing i still have the issue

Could it be the bucking?

So if there is anyone who knows whats the problem lemme know!

might, might not help but when i opened up the main assembly on my ICS and put it back together i didnt have the 3rd gear in the right rotation(flat side up). when it was like this i was kind of getting the same thing you are talking about. dont know if king arms are the same but check and see if something like that is the issue. one never knows.

This probably as nothing to do with your problem, but on my King Arms Thompson you had to be very careful when selecting safety/fire and semi/auto or it would not fire properly. Make sure the selector is pushed all the way and wont go any further!

allright heres an update;

opened the gearbox again,

wires are fine

gears are shimmed

airseal is perfect

gun cycles normally

only shit is it doesnt fire bbs

changed the hopup unit AND the outer barrel, nothing

it still shoots one bb perfectly like said before, but the oters just roll out of the fuckin barrel or jams in the inner barrel once in a while

what the hell is goin on

i have that vietnam game comin in a month or so and i cant make that piece of shit work

Part of your cycling system is the tappet/nozzle/bucking action area, so it's possible that it's cycling normally but not cycling "well", if you get my drift.

A few things to try:

- Secure your hopup unit tight against your gearbox, whether with tape, o-rings, or whatever. Make sure it's tight and not moving.
- Try a few other buckings. It's possible the bucking lips are too tight for a BB to go through, or too loose.
- Inspect your tappet plate and make sure the end that engages your sector gear isn't worn down or something.

If you are having BB-roll or double feeding, it can often result from a bucking that is either too tight or too loose, or a tappet/nozzle cycle that is whack, or something in that area.

Take your hopup unit and barrel out of your gun and place a BB up against the bucking lips. It should stay in place and not fall into the barrel. Now take a thin hex driver or a needle (I use a knitting needle) and gently tap the BB. It should fall into the barrel. Make sure the other end of the barrel isn't sealed when you're doing this test :)

edit: Problems like this can also stem from the wrong size nozzle. If you find that your compression is amazing in one shot and terrible in the next shot, it's possible your nozzle is too long or engages your bucking lips improperly (thereby making them act like they're too loose), slamming the BB far into the barrel before you actually take the shot, causing its travel distance to be shortened.

what kind of ammo are you using?

I had a similar problem. ensure the spring that goes on the outside front of the hop up unit is not missing...

UPDATE!

hop up spring is not missing
bucking is brand new

tappet plate was weak and bent a little, replaced with a G&G tappet plate and spring

im using .25g BB Bastard


Still not shooting

make sure that stupid anti reversal latch is in place!

this isn't a joke, does the gun work if you hold it upside down?

hummm i think it may be a problem with the nozzle, it may be a bit too long
i will try to file it down a bit and see what happens

my patience is running out with that gun hehe :hammer:

What happens if you shoot slightly upward with hop up off?

Nozzle should be 21.4mm

filed one milimetre of the nozzle
tested again and.... fuck all same trouble

I had the same issue with my King Arms M4 when I first got it. I was able to fix the issue after I replaced the hopup rubber with a PDI w hold and got new mags. The brunt of the issue was caused by the poor feeding of the King Arms high-cap mag that the gun came with.

You however have said you have tried other mags. What are you using to test it now? King Arms rifles are picky with the mags you use and specifically how they seat.