980 fps with a 25 gr pellet is some serious stank! gotta love crosman guns for their ease in modding. keep posting the mods! always cool to see what others are doing and coming up with.
VTmachtech,I can get to to 980 but I turned it down so for shot count. I Did not do a string at full power. That speed is too fast for pellets in general. so I turn it down a couple of turns. About the factory setting, mine was shooting about 840-850 from factory with the JSBs. This is normal to all guns. Don't look at the advertised speeds. Once I maxed out all the setting I was getting 870-880. But compare the first chart to the second and look at the efficiency. Dave,I will do that when I get a chance. I need to figure out if I will turn the power down some more to see if I get 24 shots with in the -4% spread. That would be sweat. 3 mags at about 42-43 fpe will be perfect and that will put the average around 880. I just don't know if that would be enough air saving to gain 4 shots. probably 2.
Degassed it today. And worked on the Valve.Specs: Tport: 0.156 Barrel Port: 0.156 Valve: Throat: 0.210 Valve Exit port: 0.167 Intake: I opened it as mush as possible and still have material to hold the spring. Also drilled two hows to allow outer flow.Now The pictures:Here is the mod to the shroud holder:There has been a significant power gain. I'm topping out at 980 with JSB kings and I could add more hammer if I want to. But I brought my hammer down to about ave of 890. My shot count increased significantly and my efficiency went from to 1.304.
You might be surprised as to what you can do in terms of accuracy with the Kings at high speed. My Mrod will stack Kings all day long in the high 900s. I don't see why any other Mrod wouldn't.Your shot count turned down is awesome. Much more efficient than my gun. How did you turn it down? Did you mostly rely on the velocity screw? I can't get my modded valve down to a lower velocity unless I use Bstaley buffers or tune for a low psi fill. I always run my velocity port screw wide open.
So with the valve and port changes you increased you shot count 50%? That is incredible! From 21 shots to 30 shots at the same power level, if I am reading the tables correctly?I wish I could have that type of improvement in my .22 Marauder!
Had Some time today to shot some groups. I was shooting with a bipod and no rear bag and using the magazine. Conditions where 40 degrees with little to no wind. Distance of 40 yards.This group is of 5 shots with JSB kingsThis group is of 8 shots with JSB KingsSuper nice. Next time I'll will shot from my stand to see how it improves. The small squares in the paper target are 5.5mm squares. this can give you an idea of the group size. I seam to be getting 3 magazines before the POI start to drop. I'm filling up to 3100 psi