ICS CXP 16 L - I broke the laws of physics

[SCAR_Jester]

Hey all,

Right so my gun's been upgraded a fair bit, tuned and all the rest of it. Fires like a beaut with pretty decent range, accuracy and about 20rps. All round I love it.

Just chrono'd the thing at its sitting at 255fps ("what?!") so I hand it to a tech as about 6 months ago it was sitting at 330fps. He tries everything but cant find the problem,

now here's the weird bit.

my upper GB in my gun = 255fps (w/ stock barrel)

my upper GB in his gun = 290fps (w/ stock barrel)

his upper GB in his gun = 360fps

his upper GB in my gun = 360fps

So in conclusion I suspect there is so magic force that doesnt like the combo of my GB in my gun. The realist loss of 40fps is after 2 years of use and a fair altitude change possibly. but how on earth am I seeing a decrease of fps in only my upper?

Any help would be greatly appreciated

Thanks

- Corky

P.S. Air seals, grease, worn parts etc etc etc. all checked, the gun is fine.

 

[Monty]

Hop up probably sits better on his receiver.

 

[Sitting Duck]

your nozzle makes contact & seals better with his bucking

&

your nozzle doesn't make great perfect seal with your bucking

His nozzle is sealing perfectly with both - he may have shaved the tappet plate a little

his nozzle might be 0.2mm longer

that is my guess - the variation may appear nozzle-bucking seal

other than that - the answer is fuctifino, now what what is the question again ???

 

[SCAR_Jester]

Forgot to mention we tried both his barrel and mine in both receivers. same nozzle, both ics stock hop units (both new I believe), same rubber too, still getting the fps problems.

Big question was any reason why the fps would be lower in my receiver and not his? His is one of the old ICS m4's but then again the cxp-16 uses an m4 receiver.

The reason I think its a problem is that it used to be fine.

 

[Monty]

Because the hop-up unit on his M4 receiver, allows it to push up against the gearbox, whereas yours is probably missing something to allow it to push up against the gearbox to ensure a good seal. That's all I can think of,

 

[Sitting Duck]

still stabbing at nozzle to bucking area.....

shave front of your tappet plate to help nozzle move forward & seal a little bit better

you may have a slight leak at nozzle/bucking in your gun - or not quite 101% sealing and blowing in use

0.1mm can make a difference

most tappet plates are about 2.5mm thick at front....

oh f*ck it gimme a sec....

do not assume everything is always 101% compatible:

(or works 101% the same in each/different guns/builds)

slight deviations in manufacturing, revisions, materials, wear, nozzle lengths vary, tappets as pic shows vary

wear and tear, bit of crap in there all can translate into different results....

your gun has dropped 35fps in 2 yrs - sounds bout right

check nozzle, tappet plate - maybe sand it, ensure tappet spring is good - lose a coil maybe

new spring or add spacer

reckon that should sort it

 

[SCAR_Jester]

Because the hop-up unit on his M4 receiver, allows it to push up against the gearbox, whereas yours is probably missing something to allow it to push up against the gearbox to ensure a good seal. That's all I can think of,

Both have a spring to push against the GB, and also a small spring on the hop unit, its solid and even with a mag in it doesnt move at all.

still stabbing at nozzle to bucking area.....

shave front of your tappet plate to help nozzle move forward & seal a little bit better

you may have a slight leak at nozzle/bucking in your gun - or not quite 101% sealing and blowing in use

0.1mm can make a difference

most tappet plates are about 2.5mm thick at front....

oh f*ck it gimme a sec....

do not assume everything is always 101% compatible:

(or works 101% the same in each/different guns/builds)

slight deviations in manufacturing, revisions, materials, wear, nozzle lengths vary, tappets as pic shows vary

wear and tear, bit of crap in there all can translate into different results....

your gun has dropped 35fps in 2 yrs - sounds bout right

check nozzle, tappet plate - maybe sand it, ensure tappet spring is good - lose a coil maybe

new spring or add spacer

reckon that should sort it

Will recheck seal as stated with the tappet plate, last resort I've got a thin o-ring I can wedge in behind the hop unit but probably the length of the nozzle/tappet plate combo will help.

In any case even if I fixed this the thing needs a new spring I think regardless. especially when I want to use .25's at woodland fields and not cqb.

Thanks for the suggestions guys.

 

[Sitting Duck]

There are so many many deviations in just the front end of gearboxes.....

no really....

Gearbox front ends tend to be about 3mm - sometimes a bit lower 2.6mm

v2's and v3's differ also in the total possible tappet/nozzle retraction varies:

11.44 on a v3 & 9.81 on a v2:

now add in deviations in tappet plate thickness, nozzle lengths etc.....

you can see how so much different stuff can feed/seal great or completely crap

take that v2 with 9.81mm tappet travel

use a big tappet plate like 2.62mm

that leaves a max nozzle "window" of 7.19mm

now that nozzle has to seal against bucking - probably requiring a 1mm to seal nicely in use

that leaves 6.19mm to feed a 5.95mm bb

0.24mm

that in theory allows for less than a quarter of a mm for that bb to chamber easily at speed and that is everything has no wear at all and the window itself is correct position.....

the v3 with a thinner/shaved tappet....

11.44mm minus a 1.98mm leaves you with 9.46mm window to feed n seal

that is quite a difference giving it more leeway than 7.19mm to chamber

Note this v3 was one of them JG types that can use them v3 cylinder heads with the "lug" on it

Cyma v3's I don't think have the cut-out or lug cylinder head - but haven't measured them in detail

This just shows that often some v3's have longer tappet/nozzle " window " or travel than v2's in general

but shows that there are many things that can affect stuff like sealing/feeding blah blah blah.....

Alas the teching mofo tutorials do not tell you about paracetamol/ibuprofen that is often required when you realise that some $hit just don't quite work as it should

hence reason why sometimes a tappet plate might need to be shaved to assist the nozzle pushing forward a smidge more & help stuff seal better

or

it don't feed 101% if nozzle does clear properly on retraction to chamber a bb effectively

oooh the joys of these toys

Yes I have a sad life....

but just pointing out that a lot of stuff really varies and differs quite a bit - bit of wear n tear

no wonder these toy guns cause so many headaches

just stuff for us to check - jeez that list keeps growing

but it is more of a demo of stuff to look at if your gun is playing up

reckon shave tappet a little would help to get that nozzle to seal a bit better if nozzle is in good shape

best of luck in further diagnostics & trial/error stuff