Paintball

[CJOttawa]

Background
One of the challenges of a very short-barreled marker is accelerating paint to 300fps in short distances. This involves heavier hammer springing than required for a comparable gun with a longer barrel, say, an 8-12" barreled Phantom.

Examples:

• red main spring and blue valve spring gives my Redux (standard, 6.25 inch barrel) good field velocity; 280-300fps easily
• blue main spring and blue valve spring nets about 280fps on a 12" barreled Trracer or Phantom.

Light Springing For Consistency
In an attempt to gain some efficiency and consistency, per this thread, I tried a blue main spring and yellow valve spring.

The result was velocity at the lower end of acceptable, around 260fps with a milled, 25gram hammer.

Assuming we accept the reduced velocity, I noticed a new problem: valve "squeak".

Valve Squeak
Valve squeak...what the...? I'll explain.

• Near the end of a 12-gram, reduced pressure in the valve holds the cupseal against the valve seat with less force.
• With a strong valve spring, the spring and gas pressure combine to hold the valve closed.
• With a weak valve spring and low gas pressure, the relatively strong main spring required for a short-barreled gun pushes the valve open slightly on cocking.
• This releases a small amount of gas and causes the gun to "squeak."

I'm hypothesizing a loss of efficiency with short barreled guns and light valve springing on account of this lost gas during cocking.

With a red hammer/blue valve spring combination and a milled, 25-gram hammer, I never had this happen.

[Greenmtnphantom]

Did the consistency improve as expected?

[CJOttawa]

Originally Posted by greenmtnphantom

Did the consistency improve as expected?

I haven't sat down with a chronograph yet to test that empirically but the intent of light springing was to increase the number of consistent shots near the end of the cartridge at the expense of a sharp drop off when gas runs out.

I suspect enough shots are lost from "valve squeak" to negate any benefit of the lighter spring combination.

___________________________

I am considering one modification: adding a collar around the valve seat to increase sealing surface area. This would increase the force needed to open the valve, in proportion to gas pressure, and help to hold the valve closed even as pressure drops.

3022 has written about this here: Snipers on 12 grams / on CO2 Discussion

[Greenmtnphantom]

Yeah I've read it, I've tried the lighter valve spring theory, and I'm going to continue to mess around with it a little but I have not had very good results so far. That said I haven't set it up exactly as he said either.

[ironchef97]

Ahhh interesting...I wonder what the optimal setup really is then..

[DSA]

For my Line SI and other Nelson guns I have owned I have always used Red Main and Yellow Valve springing combos. However after 2 yrs of owning my Redux the Red Main and Green Valve have been the optimum combo for extreme hot weather low humidity temps encountered in West Texas.

[CJOttawa]

Originally Posted by DSA

For my Line SI and other Nelson guns I have owned I have always used Red Main and Yellow Valve springing combos. However after 2 yrs of owning my Redux the Red Main and Green Valve have been the optimum combo for extreme hot weather low humidity temps encountered in West Texas.

You sure you have those the right way around DSA?

Red (strong) main hammer spring + yellow (weak) valve spring would yield VERY high velocity on most Nelson guns.

[DSA]

Originally Posted by cjottawa

You sure you have those the right way around DSA?

Red (strong) main hammer spring + yellow (weak) valve spring would yield VERY high velocity on most Nelson guns.

Yep thats the way I roll "Hard n Heavy!" I want it to hurt real bad when I hit you

[CJOttawa]

Originally Posted by DSA

Yep thats the way I roll "Hard n Heavy!" I want it to hurt real bad when I hit you

You running small powertubes? (0, 2, 3, 4?)

[DSA]

Nope my power tube is big and long!