Anyone had any problems with Classic Army metal M4 bodies?

[skapunkninja]

Morning all.
i am so stumped on this one, i could scream!
Has any one had any problems with CA M4 metal bodies? Heres the story....

I've had an old JG M4 for ages that i use as a loaner. A few weeks back someone managed to snap the plastic body in half. "no big deal" i though, "i'll just get a new body".
So my new metal body turned up today. i got it all fitted, chronoed.... 32fps. hmmmm. Now this gearbox has always been putting out 340 fps, so i thought there must be an airleak. NOPE! everything is tight, hop is butted right up against the GB, rubbers ok, hop units fine, all seems fine.

Ive been at this all day now. Numerous gearbox strips, new nozzle, new m120 spring, new piston and cylinder, 4 different hop units, 2 barrels a dozen different hip rubbers, 15 different mags (high and midcap). I even went as far as to take the gearbox out of my G&P m16, and fit it into the m4, but still to no avail! the best i've managed to get is 120fps, and that was only for a few shots.

I've tried Excel, Madbull and ICS BB's, 2 different chrono's (just incase), and now i just dont know where to go next.
Im a pretty experienced airsoft tech, been fixing guns for about 6 years, and ive NEVER been this stuck.

Anyone got any thoughts?

[Opossum]

Re: Anyone had any problems with Classic Army metal M4 bodies?

I have an M4 built up from what I believe to be CA upper and lower and everything's been fine. Could it be the hop unit leaking air or something physically blocking the shot? I know you checked the hop unit but I had an ICS gun that didn't like the new hop unit I gave it and gave me crap fps.

How does it shoot? Poor range, accuracy etc.? Does it sound okay?

[Bachelarius]

Re: Anyone had any problems with Classic Army metal M4 bodies?

JG has been known to use oddly sized hop units, may be the issue here. But have a look at the various air leak tests and find out where you are losing it. Try shining a light up the feed tube and look down the barrel, when the air nozzle is fully forwards or chamber 1 bb and then stuff a bit of tissue down hop unit's the feed tube. If it gets shot out, you will know that it is an air leak there.

You may end up having to go for a new hop unit, but do the tests first.

[skapunkninja]

Re: Anyone had any problems with Classic Army metal M4 bodies?

Cheers guys.
I've tried 4 hop units, madbull, classic army, prometheus and a JG, none of them made any difference.
I'll recheck for airleaks when I get home. It certainly seems like a leak.
After posting last night I fit the gearbox into another plastic body, and it works perfectly. I really want to use the metal body though...

[MONSTERC10]

Re: Anyone had any problems with Classic Army metal M4 bodies?

Try slotting the hop unit onto the gearbox with no upper , just make sure it slots all the way on , some times they meet up but the part that slots over the nozzle will not quite fit inside the end of the gear box , causing a massive air leak as the loading nozzle wont go all the way upto the hop rubber inside the unit . If this is the case just give it a quick file around the edge so it slots in and you should be fine . Could be a very easy to fix problem thats been over looked , as ive seen it alot of times in the past .
Also sometimes mix and matched gearboxes and bodys can have loads of problems as i'm sure your aware , somtimes they all work fine with a perfect seal on everything , untill you fit a mag , so thats also worth checking with the dust cover open with a mag fitted to make sure the mag isnt pulling the hop unit away from the gearbox , as this can cause double feeding , bad range , and well just loads of crap .