Air Arms Owners Club

Hi, when I had my s510 a few years ago I set it up with the Venturi screw wound all the way out and reduced the power by screwing the firing pot in a little.

Admittedly this was a pain in the A to set up as I had to strip it about 4 times to get the power to the correct level but I found that it made the rifle more consistent over a full shot string and also meant that in theory the rifle could never go over power without stripping the gun.

Am now thinking of doing the same with my MPR , but am just wandering if anyone here would know where abouts to set the firing pot at, just to save me having to strip it down so many times.

I know the standard setting is about 57.5mn but was gonna start with 55mm and see what I get, but if anyone knows for sure what setting would get me 780fps then please let me know. (Wish I had made a note of it when I did the 510 now)
Many thanks , Sean

I have done the same to my 510
I had pot set at 53mm with a 40g hammer

Thanks for the reply, is 40g the standard hammer weight or have you modified it?

The original hammers are 45g
I turned it down and down and down to see what weight worked best with my settings and 40g was bang on, then bought another from Julian, the lighter one I kept for a planned diy reg attempt

Thanks for the info, what sort of difference did it make?

Did it flatten the power curve or have a significant effect on the FPS spread?

Would love to see any chrono strings/graphs if you have any.

I have just put mine back together set at 55mm but still need to use the Venturi screw to tune it down.
I really need to get my new scope set up so am gonna just leave it at that for the moment but will probably change it next time I have it apart.

What sort of power level do you get @53mm with the standard 45g hammer? Would that be over 12ft lbs?

Just thinkin that if I wanted to leave the hammer as it is, to achieve 11.3ft lbs /780 FPS then may need to go down to 50-52mm ?

I removed adjuster as I thought Id make the other parts work better, Im no expert and someone might chip in with their findings, but I found less pot lenth helped lower power, make more shots and better consistancy. But chasing things I went past these and found things soon get messy

Its a balancing act and the smallest thing changes things, somtimes drastically

I then chose to fit a lane reg, this took a bit of fine tuning but it seemed easier as the air pressure is consistant so your settings are more focused, that said Im still tweaking to find the impossible

The reg thing has got better as Im just fitting another to my .22 and now exploring hammer travel not just weight/speed

Resurrection of an old topic.

I have removed the reg from my 500, set the pot to 57mm but with a 37gr hammer. Running to high, got to reduce pot length. Going to try 56 with 37.
37 worked really well with the reg though