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Hi everyone so I'm in the process of building my first sniper. It's going to be a vsr 10 based build. Thanks to this forum and it's people I could finally decide on a few parts. The only part I need clarity on is the spring. My field's fps limit for a dedicated sniper role is 500fps.

Acording to 1tonne's post I should use a M160 beacuase it wil settel at just about the right fps.

My problem however, is that someone with a similar build to the that I plan to put together got about +-580fps with a airsoftpro M160(I guess it has got to do with te airseal of the build being almost perfect or some thing. And maybe the barrel length as it is 428mm at 6.04mm) . This is obviously to high for my field. So I reckoned I could use a M150 to get closer to 500fps and if I'm stil over 500fps weight my piston to get just below the desired fps.

If anyone could correct my thinking or give some advise it would be highly apreciated.
 

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Non-linear vs. linear spring

so which would be better for a JC build, linear or non-linear springs, since you said that piston needs to travel slow at first then fast at the end.

i found this also in another forum......
"So I've been asked the question "What's the difference between linear and non-linear springs?" several times, so I figured I'd make a post here for reference.

There's a little thing called Hooke's Law that governs the forces and displacement characteristics of springs. This law states F=-kx with 'F' equaling the force exerted, 'x' equaling the displacement distance of the spring, and 'k' representing the spring constant value of that particular spring. Now, what this means is that if the spring is considered linear, its 'k' value is constant. If the spring is non-linear, its 'k' value varies along the length of the spring.

Now that the basic concepts are out of the way, it's time we actually look at what this means with respect to airsoft springs. If you pick a spring, and are unsure what type it is, there is a very simple way to determine it. Please note, do not mistake this as a method for determining the strength of the spring, or the 'k' value. You could determine this value by actually testing the spring, but that's another concept for another day. Anyway, just by visual inspection, if all the coils over the entire length of the spring are equally spaced out, then you have a linear spring. If there are sections of the spring where the coils are closer together or are a bit wider than other parts of the spring, it is a non-linear spring.

Okay, so now you know the basics and how to identify the spring type by visual inspection, it's time I answer another question I get following the first question a stated above: "What's the difference in using one over the other?"

Basically the point is that with a non-linear spring, at the beginning of the compression cycle, the spring constant 'k' is lower and the spring can therefore be compressed more easily. This puts less stress on the other internal components such as the piston teeth and gears because the spring is easier to compress. As the spring is compressed, the constant increases which eventually equates it to linear springs of the same rating strength-wise. Think of it this way, non-linear springs come kind of in stages, sorta like putting several small springs with different 'k' values together.

If you have any questions, feel free to ask."
 

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Discussion Starter · #85 ·
I tried linear and non linear in JC builds thinking that one would be better than the other but in the end, I found no difference. Both produced similar JC.
What have other people found?
 

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Does anyone know the relative length and outer diameter differences of springs for the various platforms? For example, are VSR10 springs longer than APS2 springs?

I recently bought a VSR10 Laylax SP170 spring for my rifle, which was quite a bit (~1.5in) longer than the stock spring. It shot great at first, but quickly dropped down to the 2J range, and the only thing I can attribute the power loss to is the fact the spring is much shorter than when first installed.

I could not find anything regarding this topic, which is odd to me as this is a fundamental part of spring physics.
 

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You very likely got a bad spring, as in the Nerf hobby you just don't want a spring with empty space, or a spring that at full compression is too long to catch in your gun.

Laylax stuff isn't exactly hit or miss, but it's not as reliable as PDI I'm terms of batch quality as seen by their barrels (rumored, can't say I've seen it myself as I can get a better barrel for less)
I'd suggest that you get another spring and go again, as it could have been a shitty temper or something.
I'd look at about any spring, especially Lambda or PDI, or maybe an APS2 like Lambda, PDI, Modify, or Rapax.
 

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NOTE: If your fps is just over your club limit, do not cut the spring. Instead, wrap solder around the piston (If you have the space to do this) and then use a little electrical tape to hold it on. This will slow the piston down and then you should be under your limit. You can remove the solder once the spring has worn in.

To make your FPS more consistent and to give your spring longevity you are best to choose a spring that is bigger than what you need and then cut it down. If done right the spring, once cut, should only just be compressed a little in the cylinder. For example, in my VSR10 I use a Laylax SP190 spring that can produce really massive amounts of energy (way more than I need). I cut a few coils off the spring so that it is only just compressed about 10mm when the gun is not cocked. This means that over the period of time between games the spring does not lose its rigidity.
Also once the spring does start to wear down you can make a little round washer/spacer to fit behind the spring on the guide to put the fps back up a little. With weaker springs you will need to put in a bigger spacer to make a reasonable difference but with stronger springs that have thicker wires, you will only need a little spacer.

Note: When choosing the spring, only get one that is about 50-70fps above your desired rating that you wish for. If you go too big then you will have to cut more coils off the spring and then the spring may fit loosely in your cylinder and may bounce around. Also, before cutting the spring, leave it in your cylinder for 2-3 weeks. This will mean that the initial main loss of energy should have happened and the spring should have stabilized more.

Another interesting note is that manufacturers often test the "M" ratings on springs with a short inner barrel of 220mm x 6.08mm. So if it says "M150" then it is most likely 492fps (150 meters a second)using 0.2gm bb's with a 220mm long inner barrel. Often in your own setup, the fps will be higher as you may have a longer inner barrel

Here is a rough guide for spring ratings once they have worn in.
M90 = 270-285fps
M100 = 300-315fps
M110 = 330-345fps
M120 = 360-375fps
M130 = 390-405fps
M140 = 420-435fps
M150 = 450-465fps
M160 = 480-495fps
M170 = 510-525fps
M180 = 540-555fps
M190 = 570-585fps
Or
SP130 = 445fps
SP140 = 480fps
SP150 = 510fps
SP160 = 545fps
SP170 = 581fps
SP180 = 615fps
SP190 = 650fps
Or
PDI 100% = 290-300fps
PDI 120% = 320-330fps
PDI 140% = 335-345fps
PDI 150% = 350-360fps
PDI 170% = 395-405fps
PDI 210% = 420-430fps
PDI 240% = 450-460fps
PDI 270% = 480-490fps
PDI 300% = 520-530fps

One good thing to note is that Laylax VSR10 springs will also work in a Maruzen/WELL L96 but you may have to drill out the piston a little. Most aftermarket L96 pistons will fit a VSR spring straight off without modification.
Even though Laylax springs cost a little more, I really rate them as they last a lot longer than most other springs.

How to cut a spring
Step 1: Cut the spring with side cutters or hack saw. Normally 1 coil will be about 20fps on a M130 spring. The bigger the spring the more FPS a coil will be. So a M190 spring is normally about 30 fps per coil. (This is only a guideline as not all brands or springs are the same). If you are wanting to take off 2 coils then cut just before 2 coils. So cut about 1 and 3/4 coils.





Step 2:Heat the spring and flatten the pointed part that sticks out.



Step 3:Grind any sharp points



Finished



Also note that spring lengths can effect joule creep.
If a spring has been cut to be the same length as the cylinder, the spring will apply not much force when the piston has reached the end of its travel because the spring will be fully extended. This will mean that the piston will travel fast at the start of its movement but then only gain very little acceleration after the initial burst.
When making a JC rifle, you want the piston to travel slow as the start of its movement and fast at the end. So in this instance, long springs are good.
Hi there, i'm just using Element M155ST spring for my DMR setup on M4A1..with 0.20g (548fps -max 566fps) with 0.25g (507fps- max 511fps). So far its great.
 

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Discussion Starter · #90 ·
That is a little high but not unexpected. Different springs can have slightly different outcomes. Also, if it is new, it will wear in to about 510fps
 
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