is it the seals

One shot is all you will get out of a standard size springer set up. It's all I'm looking at. The increase in volume for doing multiple shots I have no dought would be to large and heavy. The addition of a larger storage chamber for high pressure would facilitate the ability for more than one shot but need multiple pumps. Im working on the principle of springer convenience of one pump, no outside precharging and getting rid of the recoil while shooting. If you want to increase the air chamber size for more than one shot your going to need custom seals, custom piston, custom receiver. I'm trying for the idea adapting a cheap air rifle for experimentation for proof of concept.
What diameter air chamber do you think is the largest you can go without getting to big and I'll look at the volumes and pressure, see how much air a single pump will store under pressure and volume, the increase of friction over seal diameter, increase of heat through port to high pressure chamber, increased piston weight (though design could drop that) extra force needed to cock the barrel, etc etc, but I dought it will be more than two or three at max.
Thats if you don't want to do that yourself.
You will never get the volume storage of a pcp ( which is highly compressed from machinary using multiple compression strokes) in a single stroke action (in my view) but you can get enough for high pressure storage for a single shot from what I've looked at so far and even that may require a larger cylinder diameter or longer piston stroke to over come the loss of energy compressing into chamber. Havent worked all that out yet. Anyone who wants to and post results please do.

https://www.mediafire.com/?5mcemcyutrm

Pdf of book "Trigger to muzzle" comprehensive study of internal workings of springer air guns. More formulas for working out stuff that you can shake a stick at. Older study by 3 independent guys. Equations all relevant to modern springers guns if you have the input data.

Edited by kruzaroad - 27 Aug 2022 at 7:48am

Xyon, yes you are right it would have a big impact on power output. But I would rather a slower accurate pellet (say 550-600fps in .22) over a faster inaccurate shot.

The thing that wouldn't work is having a regulator that would allow the high flow during the shot cycle, Nothimg would be worse than having a delay in the shot cycle

Does anyone know the pressure that the piston builds up in a brake barrel?

I'm more than happy with the spacer washer out. It's 5mm and it added thump to the forward stroke. It was a noticeable difference.
I had to use a gclamp and washers to recompress it. So there is pressure there from the start. I actually hate to think how much harder it was hitting.
I was just reading an artical I stumbled on looking for friction info, about the affect of a harder springs (and gas rams in particular) having more effect on recoil when the initial jolt of the ram releasing, the than the end of stroke.

Any idea of the equation or a site I can use, to find out what the temps get too? Knowing that I could work out the decress in air. I have a simple design in my head to keep heat to a minimum entering the pressure chamber.
At 45cc the the air compressed to a third made 2bar approx.( no loss from friction or cooling in that) If I can   alculate the loss I can adjust the storage volume for when cooled.
Oh a barrel has been sent to me today free of charge. Off a returned gun with mag problems. sweeeeet