Bowkett multi-stroke pneumatic air rifle

Bowkett multi-stroke pneumatic air rifle 

With thanks to Louis. He says:

I recently acquired this John Bowkett multi stroke pneumatic in .22 caliber, through a collector in Belgium.
John built it in the early eighties, and it's still going strong.
I tested the gun last Saturday evening. It packs a punch. From 2 pumps onwards, the compound lever setup surpasses the UK legal limit (which ain't a problem in the country of windmills and green cigarettes). It was designed for pest control if I have understood correctly, in situations where a firearm wouldn't be safe to use.
The trigger is great. Pumping takes a bit of practice, but once you know how it works, it's easy.
I like to have the gun on my lap, so that the lever can go all the way down to the floor, and then I can press the lever back home in a controlled way with both hands.

Louis and John Bowkett himself recorded the following power figures:

Louis said:

I finally chrony'd the gun yesterday evening, when the missus was out.
1 pump, 7 ft/lbs
2 pumps, 14 ft/lbs (mind you, no power limit for airguns over here)
3 pumps, 21 ft/lbs
That's with 15.89 gr JSB's.
The pumping remains easy, with the gun on my lap, using both hands to push the lever back home in a controlled way.
The Bowkett carbon silencer I already had, came in handy.

He added:

I asked John, and he told me that this gun should make significant increases per pump up to 9 pumps.

He found his recordings for 4, 5 and 6 pumps:
23, 26.5, 28.5 ft/lbs

The goal was really to get a good velocity of all round use at one, two and three pumps but if sitting in a hide and having to use a longer range than normal the extra velocity above 3 would be useful.

I think it's an amazing gun, I've never seen anything as powerful in the form of a pumper.
Also, the workmanship is great. I like John's out of the box design, the simplicity of the design (although a lot of thought and testing must have gone into the valve design), and the elm stock. It's different, and John's designs are never ever boring.

This is how you set the valve: