first post about tuning .25 and declining velocities

[FZ09]

Hello
I have not been having any success in tuning my Gen II .25 cal marauder to get a curve that increases then falls. I fill to 3000 psi and shoot JSB kings 25.39.
I gave up on the A team method and used the Hill method.

Below is the data table for the original curve (blue) as the gun came from the factory The green and yellow are the 2 strings I shot with the hill set up which is as follows. HS 3, HT 0, meter screw 5.5ccw

In the data table I show the averages for each complete string and then the first ten shots for the hill strings which is ver interesting. The averages of the first ten shots of each hill string are very close at 769.13 and 769.19.

I guess I could live with this but don't know how to improve it.

Does anyone think this is a good place to stop or should I make adjustments or replace the springs? 12.5 lb spring perhaps.

thanks for your help


data and related graph below




graph

[RayK]

Your vms must be constricted (Perhaps it closed some when you installed the set screw on top).

Those velocities are very low for Kings - even with all stock parts.

I've never heard of a Hill tuning methods, but I know Tim Hill sells modified valves (opened up) that work pretty well.

Ray