Is professional tuning worth it?

[Shed tuner]

Also what is a tuning kit?
If it's a well fitting guide and top hat made from acetal and a decent Spring, I can and have made quite a few kits of my own in that case.

I agree and this is half the issue, But I was thinking more of piston nose extensions to shorten the stroke to volumes optomised for Uk power levels as well. And springs selected for shot cycle (oftern softer and longer for larger bores to counteract bouce), and possibly superior quality piston seals.

However, if you have a lathe, some skill and some idea of what you are doing, I'd suggest you could get 90% of the benefit yourself for 5% of the cost (and your time, of course)

[Daveo]

I agree and this is half the issue, But I was thinking more of piston nose extensions to shorten the stroke to volumes optomised for Uk power levels as well. And springs selected for shot cycle (oftern softer and longer for larger bores to counteract bouce), and possibly superior quality piston seals.

However, if you have a lathe, some skill and some idea of what you are doing, I'd suggest you could get 90% of the benefit yourself for 5% of the cost (and your time, of course)

That's fascinating stuff.
I know people alter transfer ports too on some guns.
That's where my limited knowledge runs out.
So is this advanced stuff more about how the shot cycle feels, sort of tayloring it for the shooter?

[Shed tuner]

So is this advanced stuff more about how the shot cycle feels, sort of tayloring it for the shooter?

That's certainly part of the mix.. excessive piston bounce is just that, but balancing the stroke for faster vs softer can be a little more subjective. Smaller ports are a little softer unless the piston bounces too much, which can be counteracted with a longer, softer spring.. all interrelated. I sleeve down the TPs (from =5.5 x 12mm ) on old BSA standards and gain a foot pound and a much better shot cycle, less recoil, less slam. Extreme example, and they were made that way for a reason (the tap is reamed thorugh into the bore through the port, so the port is the same size as the calibre) but you get the idea.