Spring Change Attempted Please Help!

[Everz88]

Hi all at airsoft forum Uk!

 

brand new to the airsoft world (3 skirmishes deep) but really enjoying it! A colleague of mine gave me a rifle a think is a CM.515. Went to my local shop to see what FPS it was kicking out and was shooting around 420, I’ve attempted a spring change to bring it down, thought it had gone quite well but the BBs are now just about trickling out of the end, various google searches leading me to believe an air leak??? But would love for some one to break down in laymen’s terms the process of fault finding with it?  Even at the minute I seem to have failed!! Really enjoyed stripping the gun down! The rifle was free so although I would love to skirmish and get some use out of it it’s no massive loss if I break it during the process.

 

thanks in advance  

[Sitting Duck]

Nozzle / tappet plate must be moving coz it is chambering bb's

(Transferring bb's from mag to barrel)

 

My initial thought is did you remove the o-ring from piston

to change/stretch it but forgot to refit it ???

 

The cyma box is pretty good - tiny tiny bit qwirky but solid

The piston has a chunky alloy spacer like most cheap China guns

But spring isn't hooked in like day JG or SRC's

So changing spring is really straight forward

 

My initial thought is the o-ring is not there

The piston is off the rails and mega binding on release

(so it drags and returns slowly)

BUT if it was binding on release it would bind on retraction

so be like if you pulling a much higher spring back

 

I doubt if you installed the cylinder back to front

(does happen) but the 515 uses a full cylinder

So that rules that out

 

I'm wondering if the hop unit is fully on bucking ripped shreds or failing to mate up correctly and seal - but at same time I'm assuming it fired ok before spring change and you were just going to change spring only - so why would much change...

 

I'd remove the top receiver and with box still fitted check the nozzle moves ok, which it should do as you are chambering bb's

Place you hand near the nozzle - NEAR THE NOZZLE

you should be feeling the compression

 

What you got there is less power than a sneaky silent fart tbh

It won't move mountains or knock a cuppa tea/coffee off the table

But it will shift bits of paper or move curtains or shit like that

 

If nozzle moves and you got some blast coming out

Then chances are it is how the hop/box was reassembled or mated up together

 

Take the hop/barrel out...

Grab say 3 bb's - it might take a few attempts

Wind the hop off if it is on ultra heavy...

Practice mating the hop up to the box by hand...

Now place a BB into hop unit, mate up with box

See how it shoots

 

Might take a couple of attempts, but reckon bb will travel down garden than just dribble out of barrel

 

If so, then box is ok, the fault lies in the seal from hop to box

Usually there is a tiny spring that helps hop remain sealed against the box

 

But rather than throw more crap in the mix...

Test box works and some blast/compression

If OK then test the barrel/hop up against the box by hand

If it seems to work then a good seal was lost as you refitted the top receiver

and unlikely you need to reopen the box again

 

The box could be tilted and nozzle scraping on hop bit tbh

I'd test the box nozzle, compression blast then test hop unit by hand

as a process of elimination to where specifically the main fault might be

 

You either got a bad alignment of hop to box or missing o-ring on piston

I think the hand hop test will produce a better shot and determine if you need to open box or not

 

If you have changed other shit please be honest

But as it stands on just a spring change u reckon it was misaligned at the hop/box

 

[Everz88]

9 minutes ago, Sitting Duck said:

Nozzle / tappet plate must be moving coz it is chambering bb's

(Transferring bb's from mag to barrel)

 

My initial thought is did you remove the o-ring from piston

to change/stretch it but forgot to refit it ???

 

The cyma box is pretty good - tiny tiny bit qwirky but solid

The piston has a chunky alloy spacer like most cheap China guns

But spring isn't hooked in like day JG or SRC's

So changing spring is really straight forward

 

My initial thought is the o-ring is not there

The piston is off the rails and mega binding on release

(so it drags and returns slowly)

BUT if it was binding on release it would bind on retraction

so be like if you pulling a much higher spring back

 

I doubt if you installed the cylinder back to front

(does happen) but the 515 uses a full cylinder

So that rules that out

 

I'm wondering if the hop unit is fully on bucking ripped shreds or failing to mate up correctly and seal - but at same time I'm assuming it fired ok before spring change and you were just going to change spring only - so why would much change...

 

I'd remove the top receiver and with box still fitted check the nozzle moves ok, which it should do as you are chambering bb's

Place you hand near the nozzle - NEAR THE NOZZLE

you should be feeling the compression

 

What you got there is less power than a sneaky silent fart tbh

It won't move mountains or knock a cuppa tea/coffee off the table

But it will shift bits of paper or move curtains or shit like that

 

If nozzle moves and you got some blast coming out

Then chances are it is how the hop/box was reassembled or mated up together

 

Take the hop/barrel out...

Grab say 3 bb's - it might take a few attempts

Wind the hop off if it is on ultra heavy...

Practice mating the hop up to the box by hand...

Now place a BB into hop unit, mate up with box

See how it shoots

 

Might take a couple of attempts, but reckon bb will travel down garden than just dribble out of barrel

 

If so, then box is ok, the fault lies in the seal from hop to box

Usually there is a tiny spring that helps hop remain sealed against the box

 

But rather than throw more crap in the mix...

Test box works and some blast/compression

If OK then test the barrel/hop up against the box by hand

If it seems to work then a good seal was lost as you refitted the top receiver

and unlikely you need to reopen the box again

 

The box could be tilted and nozzle scraping on hop bit tbh

I'd test the box nozzle, compression blast then test hop unit by hand

as a process of elimination to where specifically the main fault might be

 

You either got a bad alignment of hop to box or missing o-ring on piston

I think the hand hop test will produce a better shot and determine if you need to open box or not

 

If you have changed other shit please be honest

But as it stands on just a spring change u reckon it was misaligned at the hop/box

 

Thank you sitting duck! Exactly what i was after! Allows me to break down stage by stage now, nothing but the spring changed mate, further down the line I may look at different mods but right now my only ambition is to get the FPS lower so I can skirmish! 

[Everz88]

Just to update, excuse my terminology as may be incorrect but... tapping plate was not attached to the correct bit of the nozzle! Gun now is firing as should ready for re test!! Thanks