Sweet spot for hunting

[Pestpounder]

Just watch Jim Chapman hunting prairie dogs he was using a hatsan pcp says that 2900 was the sweet spot for his air fill ,why not not fill it fill?

 

[John "spysir" Blount]

 "sweet spot" where you have the least extreme spread from your first to last shot, many like a 20fps extreme spread other use some %.
There is a balance between striker weight, spring strength, valve stem return spring and psi in the airgun.
IF there is too much psi for the striker/spring to over come you will get VERY low fps. Due to a faulty gauge I once filled a big-bore to 260bar this resulted in 0 (zero) fps, didn't move the slug at all. We have an AA410 that likes 2,700psi this allows it to start shooting at 900fps, fill it to 2,900psi and due to partial valve lock the first ( and several thereafter ) are around 800fps until it gets down to 2,700psi then it shoots just right.


John

 

[30cal]

Well its a bit of a balancing act with fill pressure, valve opening and hammer spring tension. In a non regulated gun the pressure in the air tank is pushing the valve closed. The hammer has to open the valve against this pressure. The higher the psi in the tank the harder it is for the hammer to open the valve, thus the valve doesn't open as far at highest tank pressure and so lets less air out to push the pellet. As the psi gets lower (from shooting) the hammer is able to open the valve further thus letting more air out and the pellet then goes faster until the pressure in the tank gets to low then it starts slowing again, then its time to refill. This is your shot curve. This means there is a sweet spot where the shot curve is flattest. It often starts at less than max tank pressure.
Hope this makes sense.

 

[Pestpounder]

Thank you both for this info,I hunt with..22 mrod this will help.

 

[blackdiesel]

With M-rods and Hatsan PCPs it's easy to drop in a regulator and eliminate the need to figure out the best fill pressure.