springs

[laxer47]

We opened the gearbox and took out the old spring to do a downgrade. we noticed the spring that was in the gun is shorter than the spring we put in but the fps is suposed to be lower. we then put the new spring in and closed everything up. the gun shoots but I was wondering why the one spring that i put in was longer, is this a problem.

[Palafoxx]

There are a bunch of variables that go into determining the FPS that a spring gives you. Length, alloy, spring rate, etc.

What spring did you install, and in what gun?

[laxer47]

it was the PDI 150 percent spring in a dpms panther arms m4

[Palafoxx]

The PDI 150 will put you in the upper 300's. I've only seen one shoot too close to 400 to keep in the gun, and that may have ended up well under 400 had I been able to skirmish with it right at 400 FPS. Instead, I just put a PDI 140 spring in. That has become my favorite "go-to" spring for all of my AEGs. They always end up right around 350, in my guns.
I am not familiar with the DPMS M4, or the stock spring. Did that shoot over 400 stock? Have you chrono'd it stock?

[laxer47]

I have chrono it and it shot about 420 fps but i have not yet chronoed it with the new spring.

I think my question to you is should i worry about the spring right now.

[GeneralPoraboo]

Originally Posted by laxer47

I have chrono it and it shot about 420 fps but i have not yet chronoed it with the new spring.

I think my question to you is should i worry about the spring right now.

No you shouldn't, the chance of you being over 400 FPS with a 150% is quite low

[P7hk9]

Here's what determines spring rate. http://www.stockcarproducts.com/spgtech.htm

Length isn't a determining factor.

[Coeus]

Originally Posted by P7hk9

Length isn't a determining factor.

Keep telling yourself that Lou

/That's actually pretty cool... learn somethin' every day!