M4 double/triple feeding and mumbojumbo
 

Hey guys, I need some help on that one. Here's a little story:

Got a King Arms M4. Was completely stock and working fine except for the compression that was crap and getting worse and worse.

I put a prommy 6.03mm. Use my original bucking that seemed a bit weathered but not too bad.

At my last game, compression issue was now unacceptable, as it chronied at about 260-270fps. Still gameable but like crap. During the game my Aeg started having feeding issues. I immediately thought about the bucking needing replacement.

Then I order a new piston, piston head (mask), cylinder head (mask), bearing spring guide, o-ring'd nozzle, shim set, madbull shark bucking and fishbone nub, and an Ascu2. All this should solve all my issues right?

Start replacing my stuff, try to shim my gears, without success. So I give all this to a gun doc who proceed to do it for me; check up my gears and turns out the spur gear is apparently crooked a little and need replacement. Full gear set is ordered and installed, shimmed, and all parts listed are installed.

I test the thin quickly after all that is done: seems to work fine for a few shot, put the aeg back in its case. (the original bucking/nub was still installed)

The day after I give it a try, and it doesn't feed correctly:
The first few shots get stuck in the flash hider (exited the inner but not the outer: wtf?). I clear that up and try again. Some get stuck in the inner, some get out, 2-3 at a time, like a tri-shot shotgun :/

Change the nub and bucking. Very hard to install as its much thicker than the original one. Try again, same thing. All this with hopup at 0. Turning the hopup would make the BB curve to the left a lot. But that's probably the nub not being seated correclty.

Change my inner back to the original one (6.08mm I think), same issues again...

I'm really not sure what to do about this... Anyone has some kind of idea or something?

Thanks for your help

MP

What about the mags? Have you this problem with all of them?

I'm not a technical type, but I noticed that people tend to look for big problems even when it's something simple.

Yes, same problems with all mags
I doubt they are the cause, but you've got a good point nonetheless

No More Ideas, inputs? :/

Your outerbarrel can be bent. Hard to see with naked eye though.

Some BBs will hit/get stuck at the flash hider.
Some will get stuck in the barrel because of the forced bend/flex on the barrel, causing the opening to oval a bit.

With an aluminum barrel, it takes a fall off the truck or a hit on a tree to bend them.

Hmmm I'll try to figure that one out. Might not be impossible since the Prommy inner is a bit shorter than my original one, allowing more length to get stuck in it if it's really bent.

However I'm not quite sure how it could have happened, it never got pried or anything, to my knowledge at least. Of course, in the heat of a firefight, anything can happen without you realizing...

I'll try to order a new bucking too, as I have a feeling it might add to the problems.
What bucking would be recommended? I now know the Madbull is not for my AEG... :/

Are you feeding poorly or are BB's getting stuck in the hopup unit?

Look down the hopup chamber and see if the hopup sleave is folded, bent or crinkled in any area that may causes BB's to get jammed. If it is pull the barrel out, inspect and reinstall.

Guarder Clear. Everyone I know have issues with the Madbull sharks..

Hopup bucking *looked* ok upon inspection but considering the trouble I had to insert it in the hopup chamber I wouldn't trust said inspection.

I retried my old/used bucking and while the problem still persist, I noticed a great increase in reliability. So I guess a new/better bucking will solve the problem. At least I hope.

Going to try and order one from somewhere now

Thank you for your help guys