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huahuapro

(Semi only) AEG loses FPS gradually

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Hi guys,

I've a small problem with my (Semi only) AEG gun recently and would like to ask for help or opinion. Thanks in advance!

Some informations about the gun at first:


1. It's a "custom built" M4 with V2 gearbox and M150 spring (I use my airsoft weapons only for target shooting). The whole internals are all enhanced or reinforced to hold the strong spring. Since I live in Germany, the gun can shoot semi only.

2. I ordered the gun directly from an local airsoft workshop and the folks who built the gun are pretty professional. Actually I have 2 other same guns which are also built by them (but both with M140 springs) and both of the weapons shoot still very nicely after 10,000+ shots without any issue. So I think it's unlikely that there would be a mistake or something like that inside the gearbox.

3. The only "modification" I have done after receiving the gun is swapping the original barrel and hopup rubber with a 461mm PDI .01 barrel and a Lonex 70 rubber - nothing more.



The "problem":

At the very beginning the gun shot very consistently 555 fps (max. +-3 fps) with .2g BBs and 395 fps (max. +-2 fps) with .4g BBs. But since then almost every time I chrono it (I use this gun basically once a week), the reading becomes lower. And now - after about only 1,000 shots - it shoots averagely "only" 540 fps/.2g and 385 fps/.4g (still pretty consistent though)... My chrono is the X3500 of Xcortech, so the reading should be reliable. And because I play my guns only indoor (at home actually), the barrel is also pretty clean.




And now my question:

I know all the springs will more or less settle and 15 fps drop is also not sooo dramatic. But still, since the gun has only shot about 1,000 BBs, it is still a little bit strange for me. Can a spring really lose its strength so quickly? Especially when I think about the other 2 guns of mine which have totally same internals (like I said the only difference is the spring) - they lost after more than 2 years usage and 10,000 BBs only about 5 fps... So is this really normal? Or maybe there would be some other reasons?

Thanks again!

Edited by huahuapro

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Springs settle within the first few thousand rounds. It's a break in period of sort. Hard type springs like PDI and Prometheus will settle less than soft type springs like Systema.

 

From what you have posted, your guns sounds to be operating properly and within reasonable expectations/parameters.

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Springs settle within the first few thousand rounds. It's a break in period of sort. Hard type springs like PDI and Prometheus will settle less than soft type springs like Systema.

 

From what you have posted, your guns sounds to be operating properly and within reasonable expectations/parameters.

 

Hello airborne101, thank you very much for the reply! The answer really helps me and I'm feeling also better now...

 

One more question please: how can I know if the spring is hard or soft type? What's the difference of both of the types? According to the guys of the workshop the springs which they build into the guns are their own brand and I think the springs are from China anyway...

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Experience will tell you if the spring is hard or soft type.

 

Soft springs are also longer than hard springs.

 

Springs that have various coils of great severity are soft springs.

 

Like HurricanE/SystemA

 

hurricane-m120-main-spring-896-p.jpg

 

Oh hey look what I found my post from a decade back.
4919417407_d2d39511e1_b.jpg

 

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