Autococker Main Spring Dimensions

[Lane]

Wondering if anyone has a main/hammer spring available and a set of calipers. Looking for the OD, length and wire diameter of the main spring. I know there's variation and I'll probably pick up a set from Inception Designs soon but just trying to get a head start on some design ideas. Thanks.

[Frmrspec]

I know OD is .500. I'll get the rest of the details later

[latches109]

I know OD is .500. I'll get the rest of the details later

.48” OD is stock x 1.5” length. The rest will not affect you, see below.

Buy based on spring rate and max load. Keep the dimensions so they will fit. A good general purpose spring rate is ~7lbs/in with a ~7lbs max load. The OD,ID,CS will vary slightly depending on the spring manufacture, and material.

If you like the flush IVG look, a 2” spring is what you want. Keep in mind this will add deflection.
Stock is 1.5” and anywhere from 1.5-2.5” will work.

On the longer springs make sure the compressed length is not too much that it will interfere with the hammer setting. Try to run the spring from 20-80% length. You want some pre-load to smooth things out.

[Lane]

Thanks Latches and Frmrspec! Latches you actually touched on my next question which was preload. Based on what you said it sounds like you want 20% preload minimum so a 1.5" spring compressed to 1.2" when the hammer is un-cocked. Additional compression could be added with the IVG being turned in. Along the same lines, looking at a few autococker body drawings it looks like the typical pump stroke length is around 1"? And any idea on a typical hammer weight? Looking around it seems to be around 50-60g?

[latches109]

Thanks Latches and Frmrspec! Latches you actually touched on my next question which was preload. Based on what you said it sounds like you want 20% preload minimum so a 1.5" spring compressed to 1.2" when the hammer is un-cocked. Additional compression could be added with the IVG being turned in. Along the same lines, looking at a few autococker body drawings it looks like the typical pump stroke length is around 1"? And any idea on a typical hammer weight? Looking around it seems to be around 50-60g?

Spring Compression and FPS Consistency

This guide discusses how spring compression affects spring rate and ultimately, the consistency of your paintball marker's FPS (feet per second).

Finding the Spring Sweet Spot

Try squeezing a spring between your fingers about one inch, but start at different compression lengths. For example, compress it 50% then try to squeeze 1". There's a sweet spot where it feels most responsive. This is the ideal compression range you want your spring to operate in when installed. In this range, the spring delivers consistent energy with each shot.

Factors Affecting Consistency

Several factors can affect shot consistency:

• Hammer Drag: Friction between the hammer and sear.
• Hammer Rotation: Worn or misaligned components causing the hammer to wobble.
• Hammer Size-Fit OD: Incorrect hammer size can affect drag or wobble.
• Spring Deflection: How much the spring bends under pressure.
• Air Resistance: Friction of air within the marker.
• Surface finishes: Some markers have poorly machined lower tubes.

Choosing the Right Spring Rate

The key is finding the right spring rate for your setup. Here's an example:

• Stock Valve (300psi): Use a 14 lb/in valve spring and a 6.8 lb/in hammer spring with a 30-34g hammer.
• Other Hammer wights: Adjust the spring tension using the IVG to compensate for the hammer weight or change springs when the IVG change is not ideal. Flush to 4.5 turns in is my personal max range. Past 4.5 turns in, I will increase the spring rate and back out to 2 turns in.

A Rule of Thumb for Spring Rates

For pre-2000 and 2000 model autocockers, a 2:1 ratio between valve and hammer spring rates is a good starting point. Again, try a 14 lb/in valve spring and a 7 lb/in hammer spring.

Finding Your Optimal Pressure Range

Start in the 280-350psi pressure range and experiment there, this will give you the largest window for error, and still have good air efficiency. Low pressure is a whole different animal and most markers fail at it with lack of flow from the HPR, severe loss of efficiency, or not enough velocity. All depends on what you want, I have markers I trade efficiency for sound signature.

Most autocockers will give you +-5fps, if they are swinging more than that, something can be improved. Start with the barrel and paint. For testing, I use the same barrel, and the exact same rubber reballs to test all my markers, this eliminates those variables. I know my reballs will shoot +-1fps.

[Lane]

Thanks for the information so far everyone, it's been very helpful. Another question on the valve spring, looking at images and comparing them to an 11/16 autococker valve. It looks like they measure around 1.25" long and 0.34" in diameter, is this in the ballpark for typical valve springs?

[tyronejk]

I have one unknown 11/16 valve and spring (I think it's a stock WGP one). The valve spring length is 1.2", spring OD of 0.332", and a wire diam of 0.0395"

And there are 8 active coils (plus one inactive on each end) if you wanted to calculate the spring rate.

[Lane]

Thanks tyronejk

[Ssimplechoke]

When using reball. What fps using reball equal a real paintball.

[tyronejk]

I don't think there's a fixed ratio between the two. Reballs are both lighter (if memory serves) and smaller, so it depends on pressure and barrel bore size.

[Grendel]

I shoot for 250ish with reballs then use real paint and Freak insert barrel to finish off tuning always have to up the velocity some.

[minimag03]

I've spent awhile on McMaster identifying springs that work. I have found a few options for valve and hammer springs. What type of IVG does your autococker use? And do you want as light as possible? Efficiency? Lmk and I'll send ya the options I've found.