Trouble with M4 metal body

[ujiro]

I've had a Marui M4 for a while, and it has caused me nothing but pain and frustration in attempting to upgrade it. Anyways, I got it almost all resolved, and I'll explain what I've got in it.

PDI 150% (an actual 150, not mispackaged), SystemA torque up gears (my old ones stripped when i put in a mislabelled 150 which was a 190), guarder metal bearings and shims, guarder bearing spring guide, and guarder nozzle. I also have it all in a Guarder C8 Metal body, brand new, including the metal hop up unit it came with, and the guarder 'enhanced hop up sleeve and bucking', the black ones.

Now, we seemed to have fixed almost all the of problems, except now when we have it all set up in the metal body, it misfeeds with all of my magazines. I tried using 2 different CA metal hicaps (one regular, one VN), and many STAR mags. 1 of my star mags didnt misfeed... it worked fine. But every single other magazine would misfeed. It would work for a shot or 2, and then make an awful clunk noise, and nothing would come out, and then they would come out every other shot or so, but would drop after about 10 or 15 feet.

Now, we decided to modify my old plastic TM body in order to fit the metal one piece hop up unit. When we did this, it worked fine with the CA hicaps, but not very well with the star mags; they would misfeed on occassion. But the CA hicaps worked very well. Anyone have any ideas as to what could be wrong when the inners are installed in the metal body? Or just in general what is wrong here, I want to be able to use the metal body, not my old plastic one. Thanks.

EDIT: The hop up rubber sleeve is on properly, and the little bucking nub is in properly. The spring at the top of the hop up unit which presses up against the front of the inside of the upper receiver is bent out of shape, however, although is still somewhat pointing forward. I will post pictures if necessary. I think this may be the problem, but please post your ideas.

[jtf2-phalanx]

Have you tried shooting it without the spring attached to the front of the hop-up. I know it will work sometimes as I've lost mine a few times and it seemed to work for me. it's possible the bent spring is causing the hop-up to mis-align.

[Dynamo]

or the openning on the hop rubber is too tight and not letting the BBs feed causing that "awful clunk noise", which if the BBs are not feeding into the hopchamber will cause back pressure in the cylinder stopping the piston halfway befor its fully forward.

take out the barrel with the hoprubber still on it, and check to see if BBs can pass the openning with out much force, the openning should just be large enough to not let the BBs just fall through, but not so tight that the tappet plate return spring doesnt have enough force to push it into the hop chamber.

i had this happen with my VFC HK416 and a PRO-WIN 8mm split mechbox.
i stripped 3 pistons befor i found the problem, now its a BB hose.

[ValkXB70]

Is the guarder body one of the "new types" that require copious amounts of filing to fit? I found that once I did all the modifications there were certain mag types that would misfeed and the cause was a misalignment of the hop up and the mag feed port.