Spring length differences in PDW, G36 and rifles which come with short stock springs?
 

Hi guys,

I'm tinkering with my PDW this week and have been looking to swap the M140 that came included in the gun; ~425fps or so is obviously way too hot for this gearbox / gaming, and I'm also looking for less gearbox stress and a higher RoF.

I tossed in the included stock spring, and this brought it down to a hair under 400fps. This is still too hot for me, and besides, I'm looking to increase RoF which is lacking in the stock DBoys PDW.

A few weeks ago I picked up a JG 3 spring set labelled M110, M120, M130. I tried the M110 in my JG G36 and got very low velocity through the chrono, about 270fps. To double-check if I had compression problems, I popped in the stock spring back in and the G36 went back to around the mid-350s, i.e. back to normal. I gave up and stuck with the G36's stock spring (which I had wanted to ditch because it was attached to the piston with a hook, and I wanted to try a different piston).

So this week, I tried the same JG M110 spring in my PDW to try to lower it down from 400fps. Lo and behold, I get a very low speed, below 200fps. This is a confusing result for me, since the same gun is easily getting almost all the power out of the M120 spring and passes simple compression checks, so I figure I'm missing some knowledge.

I noticed both the PDW's stock (M120) and import (M140) springs are short length springs. The G36 also came with a shorter length spring (presumably ~M110). The JG M110 that is giving me unhappy results is a longer spring spring though, which is making me wonder if I'm just picking the wrong lengths.

Am I supposed to seek out a shorter replacement spring for my PDW? Or is a spring is a spring is a spring? I'm a bit confused.

Thanks

You bought a 3-pack of chinese spring... don't ask yourself why it does not work as good as brand-name ones rated the same.

If you want to shoot around 345, get a Modify M110 for your PDW and G36C. If you want the same in a longer rifle, M16 or around 450-500mm barrel, get a M100 instead.

I have a hard time believing this.

Why does the JG (China) stock spring that came with the G36 and the DBoys (China) stock spring that came with the PDW work just fine?

I don't think Frank would be selling the spring set if it was a dud.

How much did you pay for the whole set?

A single Modify spring retails between 10$ and 15$...

Problem with theses cheap springs is not that they are always bad, it's that they are sometimes bad.

Vs. buying a brand known for consistency and reliability where the product will always perform...

Those cheap springs are known to be inconsistent in length and strength even within the same batch...

Only one way to find out :). I'm gonna give a couple Modify springs a shot and see for myself.

Oh, also, the whole set was 30 bucks if my memory is correct..

Update:

http://p.twimg.com/Ad7fL6cCEAEDufu.jpg

Took Kos-Mos's advice and picked up a couple of Modify springs. The difference from the JG springs is like night and day. With the Modify S90+ spring and some tinkering the PDW shoots 95m/s or ~312ft/s at 15 rps.

And here it is with happy new spring

http://dl.dropbox.com/u/1149620/airs...BUS_magpul.jpg

I haven't tried the S110+ spring yet, gonna have the S90 a whirl at a game this weekend.

And the moral of the story is:

a. Don't buy china crap
b. Buy cheap, buy twice
c. Don't expect quality out of quantity
d. All of the above

I would say the moral of the story is caveat emptor, do research and sometimes just go ahead and try things. I'm counting having tried out JG springs as all of those. If everyone just keeps buying the most expensive stuff there is, we'll never discover the inexpensive gems. Also, it's sometimes difficult or nearly impossible for a noob like myself to extract super detailed and up-to-date information like spring reliability out of a forum like this, so if it's up to people like me to go out there and try things, so be it :) . I'm willing.

So in the end, I would say B and C but not A, and not even B sometimes.

By the way...

SHS parts are made in China, are very cheap, and surely that means they're evil right? But at the same time, SHS is just King Arms, which we know is quite good. King arms gear sets are literally rebranded SHS gears, and people all over the net (ASM, ASR, Arnie's, etc) swear by those and run them in setups which are far more strenuous than ours (>400fps, 30rps, etc). So there are many many exceptions to the above lettered rules, and I would personally not paint an entire country with one brush.. They can make microchips, solar panels and 9 gigawatt dams, I'm sure *some* of them can handle piano wire and small plastic parts.

Just sayin'