WA M4 Cycling Oddly
 

Hey guys,

I apologize if this problem has been posted before, I took a quick look through the Doctor's Corner and did a search and nothing specific came up.

Anyway, when the gun is fired the bolt cycles very oddly. I have two mags for the gun, each mag has a different effect.

I've noticed in the other WA threads that sometimes mag type (i.e. brand) can play a factor, so I'll describe the appearance and feel of the mags as best I can to help others identify what brand they are.

Mag 1)
This mag is a heavier, darker coloured mag (I think the other threads had said this one is possibly stock WA?). When this mag is filled with gas and put into the gun to be fired, the trigger is pulled back, the hammer strikes forward but no gas comes out. I've even tried removing the upper receiver with the lower trigger assembly in tact and with a mag in, to see if the gas will release in that case, and no go.

Mag 2)
This mag is much lighter, both in weight and in colour. It's a light-ish grey, no Colt markings on the bottom I don't think.
When this mag is fired, the bolt will cycle back VERY quickly, but not all the way. The bolt cycles maybe a quarter of an inch backward (just enough to reset the trigger) and returns to battery after until the gas is out. Sometimes, it will only go for a few shots and then the rest of the gas will sputter out and the entire remaining quantity of gas will be expelled.

In any case, any and all help is appreciated. Will take any suggestions and try them, not too sure what the problem is with this gun. Apologies once again if this problem has been posted before (and moreso if it's been solved).

Thanks in advance.

Check the clearance of your bolt. When I got my prowin mags, i had to get the lower profile gas bucking cause the bolt would rub up and get stuck on it. Had the same symptoms as your first mag.

What is your gun?

How old is it?

Scratch built?

What parts are in it?

And for the mag problem... is the magcatch locking the mag when its insert, or do you need to push the mag in with force to get it to properly lock?

@Darkangel

Another fix could be to sand down the magcatch a little, like the Prowin website suggests....

Light hammer spring may be?

Thanks guys for the tips.

The clearance of my bolt seems alright. I can pull the charging handle back very easily (I know that the force with which I pull the charging handle back is probably greater than the force of the gas pushing the bolt back, but still). Also, I lubed it fresh with lithium grease just a half hour ago and tried it again, even with the reduced friction it still seems to get caught although I could swear it's cycling a little better.

Is there any way with the mags that I have now to check the clearance of my bolt and to see if it will cycle properly with them? Should I place the mags only so far in so the firing pin can hit the valve, but not high enough to engage the mag catch (where the mag would normally be position)?

Not sure what any of the answers are to your questions except for the fact that it definitely is not scratch built. The gun is an AGM M4, but all jokes about clones being crappy aside, the previous owner had said the gun gamed like a dream. To my knowledge, I'm pretty sure the entire trigger set-up (trigger, sear, hammer, etc.) was upgraded to the respective G&P parts.

As for your mag catch question, I actually find that I can push the mag a little further than is needed to engage the mag catch, and then I find that after I let go of the mag it sits back down a bit and kind of rests with its weight ON the mag catch if you can kind of imagine that. Also, no force other than the normal push of putting a mag in on any other gun is necessary for this gun.

Is there a such thing as an upgraded (i.e. more tension) hammer spring for these rifles? If so, I have a feeling that would do the trick but I thought I'd get other opinions first. Always good to ask before putting down money on anything (even though I'd imagine a spring wouldn't cost me more than a couple of bucks).

I will look into all of these, starting with maybe an upgraded hammer spring.

o kk, so mag beein able to be pushed up a little, and it going back down is jsut the rubber beeing compressed and decompressed against the nozzle assemble, so its not a mag issue....lol

Arent Stock AGM hammer springs, or at least G&P springs supposed to be stronger then the stock WA ones?

IMO check the valve knocker.... it might be damaged.... (the parts that slides in and out of the bolt catch block thinggy, (hammer hits it, and it hits the valve, releasing the gas...)

Yes there are stronger hammer spring:
http://shop.ehobbyasia.com/upgrade-p...bb-series.html
http://www.tokyo-model.com.hk/ecshop/goods.php?id=5884

Yeah I don't think it's a mag issue, but didn't hurt to try stuff to it. Also, I'm pretty sure the G&P parts replaced everything, including the spring which IIRC should be stronger than stock WA ones.

As for the valve knocker, is there anything that's supposed to be blatant about damage to it? Would it be worn down/rounded on the striker side? I can provide a picture of the valve knocker so that someone with more expertise can ascertain if there is damage to it or not. I can guess, but I wouldn't know for sure since I've never owned a WA based gun.

Thanks for the links RM, I'll definitely place an order.

yeah post a pic of the valve knocker, that then we could try to see if something is wrong with it....

It's been a long while since I've had a chance to work on this gun, but now that I have I've done and observed some things:
- I've changed the spring to a 130% RA-Tech spring courtesy of Illusion
- Fired the gun with the new spring in.

The first thing that happened when I fired the gun: it vented all the gas. So now I'm wondering if it's simply a mag issue or if there's still something wrong with my trigger set-up/valve knocker.

Any tips given with these changes in mind would be very helpful, thanks in advance.