The mysterious leak that freaks me out
 

Hey there

Right now I'm super pissed off, because I have this brand new CA aug with that super-duper TM mechbox with a bore-up kit that I put inside and the resulting FPS is amazing: 207.

everything is freaking perfect on this gearbox, from the motor to the nozzle.
there are no leaks (underwater tested) and it usually (in my other aug that's taken apart) delivers exactly what the spring inside is rated for.
before mounting it I threw in a weaker spring that I think is a MS100SP (it was laying around) so it should sit around 340.

I have 3 different barrel units wit various hop-ups and barrels, they all give the same dramatically low FPS.
I suspected the junction mechbox-hop-up, but adding foam doesn't even improve the fps, it makes it worse.
moving the mag arnoud doesn't change anything, the link is good already.
it's like whenever I improve the etancheity I lose some FPS.

What the hell is wrong with this piece of crap from outer space ?

tonight I will test the mechbox in another AEG.
after that I don't know, I'm out of solutions, almost every parts are upgrade, stock parts don't improve anything.
boo.

I just want to burn this thing.

IIRC, sometimes aug mechboxes seat too far backwards...

maybe there's a wire in the way or something..

Verify with another spring wher you know it's rating?

Sounds like a weak spring to me.

Jesus, what's with you and AUG's? :p

Try a different cylinder, and maybe try another working spring you know what the velocity of is.
Maybe your o-ring rubber on the piston head is worned out?

He said he tested the compression UNDERWATER.

is your tapplet plate stock or aftermarket?

if it's aftermarked, try a stock one if available.

It correted a 100fps drop I had

here's a pic of me testing my cylinder:
http://msnbcmedia1.msn.com/j/msnbc/C...d-1215a.h2.jpg :)

thanks all, keep it coming, I'll write a big report tonight.

Could it be the CA body and TM mechbox combination that is producing some form of incompatibility that causes the weird fps?

thats the problem right there. bad combo.

bore up kits are for springs m120 and up. Try regular cylinder.

I swapped the spring for a tougher one, no idea what it is.
(around ms110 probably)
also I swapped the tappet plate for a new one, the old one seemed a bit distorted,possibly holding the nozzle too far ???

323.8
317.3
365.1
322.6
339.6
362.9
329.3
323.8
331.8
333.1
362.1
3 fast shots
362.1
332.5
364.4
326.9
325.6
3 fast shots
322.0
325.6
358.4
356.9
362.1
325.6
325.6
326.9
332.5
328.1

what do you think?

ahh
would the irregularity come from there?

will do.
thanks a lot!

while water is and effective means for checking leaks some times you have to rember that water and air are two different mediums and you should never discount the problem simply because of one type of test. I would hazard a guess that the spring is fubared or your not getting the mech box aligment with the hop unit correct. you said you put foam in there and it made it worse? to me that says improper placement of parts in the body of the gun. I would recommend that you just simply start from scratch and dissasmble everything and go over each individual peice as you re assembly and check it from time to time as best you can. I would also recomend you take a day or two to take a break. workin on an aug is fustrating enuf without you bashing parts cause your pissed. Relax Jimski your smart and you'll figure it out. PM me if you need help.

Sincerly

Blair

regular cylinder set, same spring

276.6
325.6
268.9
283.3
276.6
276.6
273.6
278.4

282.4
281.1
278.8
282.4

How old is the M100 spring?

Bro, I'm really sorry that none of my info on this issue has been fruitful. There should really be no compatability issues with the TM box in a CA body (CA is a TM knock off anyways), as long as you are using the same brand of nozzel with the same brand of hop up unit.
If I can think of anything else, I'll pm you.

SHA DO

have you tried chronying, holding the mechbox and hop up unit/barrel together by hand? to be sure that this is not a mechbox placement problem

i use this technique to chrony my aks when i'm swapping spings

could be a loading nozzle size problem, if you have a vernier caliper you could measure the diameter of the stock one vs aftermarket one. hehehe i once accidently put a mp5 nozzle in my ak an was getting pretty shitty fps!

just my 2 cents...

How well fit is the Oring on your piston head?

hello all!
first thanks a lot for the help, that's very kind of you all.
yesterday I swapped the cylinder+head for another one ( stock TM head+systema cyl) and I'm getting decent results now.
it's still very unstable, ranging from 315 to 380.
I added grease on the base of the nozzle (outside)

The O-ring sits correctly on the piston head and in the cylinder, pressure is ok but I guess it could be better, I don't know what a good O-ring is supposed to feel like since all the guns I got stock barely had any etancheity at all :(

Tonight I'll put a lighter spring to not go above 350 fps, try to re-extend the O-ring ( I do it with a heat gun, it's very rubber-friendly )

I also checked my other AUG (a TM shorty that has a very good cylinder ensemble ), re-stretched the O-ring and threw in the CA AUG's stock spring, and I'm, getting between 315 and 330 fps with some 351 fps aliens.

now my question is: how do you achieve a consistant 349.99 FPS all the time ;) ?

anyway thanks to you guys!

that's easy... ship it to cdn_stalker and when it will comes back it will fires at 349.99999999 and will no longer needs batteries to fire :D

ahaha :)

I changed the spring and get irregular results in the lower range of 280-330, which is what I (kinda) wanted...
I got one shot at 390 fps :confused:

What BBs are you using?

ksc .20 ?

hey,
I noticed when I shoot, the head and cylinder ARE MOVING in the mechbox, I can clearly see them move under the shock of the piston.
is that supposed to happen ?
aren't those part supposed to be super-fixed in the frame?
;)

thx

cylinder head should be snug for sure, the cylinder itself may rotate in the groove a bit, that's about it. How can you tell the cylinder head is moving, is the nozzle waving about? perhaps a crack in the cylinder, if its moving a lot...

**side note, have you checked the last few teeth on your piston? and did you use oil or grease in the cylinder? have you tried tearing it down and reassembling it? maybe you'll notice something out of place

No....those aren't supposed to move at all.

:confused:

eheh ;)
well the cylinder head doesn't seem to be moving after all, however the cylinder is.
I have a new head on the way, I'll get this cylinder fixed also.

The cylinder in my AUG can move a few 1-2 mm back and forth, it's normal though, no issues with my gun.