King Arms M4A1 AEG Hop-Up Cover Issue

[Inquisitor Lok]

First i apologize if there is already a thread with this issue, but i couldn't find one using a quick search so...

But today i took apart my King Arms Full Metal M4A1 to downgrade the spring (just got the rifle the other day and needed it to shoot a bit slower for the odd indoor game). Now everything went relatively fine (it was my first time taking a rifle apart so it was a little slow, but the internals all seem to work still) but when i finally got the upper receiver back on, the fake bolt plate which gets locked into place with the charging handle to give you access to the hop-up is not working at all. It can slide back with the charging handle but when i click the bolt catch to release it will make a clicking noise but will either not move at all or will barely move. After this point it requires me to physically pull the plate forward to its initial position, and it feels quite tight.

(the part im talking about is the silver part in the mag well down below)


Now, my gut feeling is that its just being caused from a massive amount of friction between the plate and the brass looking portion of the gearbox beneath it (as in part of the piston housing). However to my knowledge nothing has really changed in terms of parts and everything fit right back where it was suppose to without trouble (and all the parts i took out are back in, i haven't forgotten a piece)

Does anyone happen to have any experience with this happening? If so how would i go about fixing it? And if not, does anyone think it would be an issue to just leave it the way it is, as i can access the hop up and all that, its just an inconvenience overall to have to pull the plate back over it. Or if it is just friction, would lubing it up likely solve it? (i'm guessing i would need to get silicon oil for that option??)

Thank you all for your help and time!!

[Styrak]

You put it together wrong. Take it apart and try again.
Or, take it to someone who knows what they're doing.

[XZIVR]

Or if you want some helpful advice, take the upper off and check that the fake bolt is sitting in the little plastic groove properly. Looks from the pics like it isn't.

The spring should pulling forward on it in a straight line, not at an angle. When you put it back together, hold your finger against it to hold it in place, then carefully slide the upper back onto the lower.

It can be finnicky, might take a couple tries to get it.

[MaciekA]

Originally Posted by Styrak

You put it together wrong. Take it apart and try again.
Or, take it to someone who knows what they're doing.

+1

This is a difficult gun to get back together, and the fake bolt is the most annoying I've seen in any M4.

In addition to this, in many cases you will want to actually get the receivers back together and verify the bolt and charging handle mechanism is all working correctly before you put the motor grip on. It sounds a bit odd, but the super-tight tolerances on the KA M4 seem to want it in that order.

[MaciekA]

Originally Posted by XZIVR

The spring should pulling forward on it in a straight line, not at an angle. When you put it back together, hold your finger against it to hold it in place, then carefully slide the upper back onto the lower.

This and you'll also want to hold the dust cover door a little bit less than fully open to allow the receivers to slide together. Otherwise hair-pulling will happen

[Inquisitor Lok]

Thanks for the tips everyone Got it all fixed. I ended up taking off both the stock and the grip and it seems like it was more the stock being to tight which was causing the problem, since as soon as i would tighten it to the max it will stop working... i also ended up lubing the parts up a bit to help.

[AnthonyG]

Thanks. My plate was tight. Loosening the buffer tube and re-tightening it made my dust cover easier to slide!