Weaker valve spring

[Pete2]

Would using a weaker valve spring mean you would need less hammer for the same results?

[tonyc]

Simplistically, yes, but there are other effects, especially if you are intending to make other modifications. You are changing the relative force on the valve from plenum pressure and spring pre-load, so the power curve will change.

There are tuners who will tell you AA design for the S4/5xxx series is spot on, others will say it can be improved. If you are fitting a reg to an unregged model, and that involves increasing the size of the transfer port, I can see the point in changing springing and hammer weight.

What are you trying to achieve?

[Pete2]

My mk2 pro target. Altering the reg and hammer I can get the fps I want but it's noisy.
Reduce reg and hammer, fps drops and it's quieter. Just thought a lighter valve spring with the lower reg would allow a lower hammer tensions well. I have a reg tester and can set it accurately.
It's a mk3 reg

[tonyc]

I can't help you on this one - no knowledge of this gun and regulator. As a general observation, I'd say you need to look out for loss of air efficiency as you reduce reg pressure.

[Blackbaronfish]

You could do away with the valve spring altogether. Then mess about with the hammer spring to get the optimal

BBF