Help Needed to Reduce FPS

[38super]

Hi All

 

I've got a Double Eagle M904G which I've upgraded and is running very nicely, accurately and consistently around 375fps with .2's.

I need to reduce the spring power and need to know how to go about it.

The current spring is 1.3mm diameter, 160mm free length, 23 coils.

Does anyone know the rating of the standard spring in the DE M904G?

Can I just trim coils of to suit (refinishing as necessary) ?

Can anyone recommend a spring that I could try?

 

TIA

Rob

 

 

[Cr0-Magnon]

Are you in the UK? With my M904 an M100 gives me around 340fps.

 

At £4 + £1.50 postage from @ak2m4 it hardly seems worth messing around with cutting.

 

https://www.ak2m4.co.uk/internal-parts/springs/zci-aeg-spring-m100

[ak2m4]

160mm with 1.3mm wire  but with only 23 coils, most probably linear spring.  Have you run through at least 1000 cycles / rounds?  Have you left the spring in a compressed state for 24 hours? 

 

Those 2 things can help to some degree.  You can trim off a coil but the spring is already quite short (may have an affect).  You could try a cheap ZCI as @Cr0-Magnon suggests or I have brand new Gearparts M95 springs.

[Adolf Hamster]

does it have a bearing on both the piston and spring guide?

 

if it does removing the piston bearing will drop it a little (maybe not enough in this case).

 

trimming is a thing but my preference tends towards changing the spring entirely.

[38super]

Thanks all.

I would prefer to change the spring. I just had no idea what to go for.

I'm happy to go with the Gearparts M95 from AK2M4. That's where all the other parts come from.

Obviously the problem is I need it for Sunday.😒

I'll order one now and maybe just have a go at cutting the existing one for a temporary fix until it turns up.

Spring ordered from ak2m4.

Many thanks

Rob

[ak2m4]

I'll post out this afternoon, there's a chance it'll arrive by tomorrow.

[38super]

30 minutes ago, ak2m4 said:

I'll post out this afternoon, there's a chance it'll arrive by tomorrow.

That's great. Thank you.

I'll keep everything crossed.

[38super]

On 16/04/2021 at 15:22, ak2m4 said:

I'll post out this afternoon, there's a chance it'll arrive by tomorrow.

 

My grateful thanks go to AK2M4 for getting the new spring to me on Saturday morning and saving my day today.

M95 spring (rated 310 fps) brought my gun down from 375 to 338-340 with 0.2's

No idea why I get 340 from a 310 spring but it passed chrono today. That'll do for me.

[ak2m4]

1 hour ago, 38super said:

 

My grateful thanks go to AK2M4 for getting the new spring to me on Saturday morning and saving my day today.

M95 spring (rated 310 fps) brought my gun down from 375 to 338-340 with 0.2's

No idea why I get 340 from a 310 spring but it passed chrono today. That'll do for me.

 

That is perfect, I'm guessing you have a bearing on the spring guide and bearing on the piston head?  Bumps up the fps a little.

[38super]

17 minutes ago, ak2m4 said:

 

That is perfect, I'm guessing you have a bearing on the spring guide and bearing on the piston head?  Bumps up the fps a little.

Definitely one on the spring guide and I think I remember one on the piston. Thanks for the info and your help.