Airmasters Tune information.

[MartynB]

The last FWB pictured above is simply bloody gorgeous. It would be even better with a slim elegant muzzle weight. One of the nicest looking air rifles I have ever seen.

Second that

[Zomboid]

More likes...

Ridiculously good looking rifles.

[Muskett]

Woof!
I once tried to convince my father that the investment in a premium 12ft\lbs air rifle was worth every penny. His view was: ""Whats wrong with a 4.10!?"
There was great reluctance to invest in higher cost field rifles. The Target Rifle brigade had their specialised machines, but field shooters came second best.
Much must be that the previous generations could have whatever they liked. Few restrictions, guns were guns and only shotguns and certain safari rifles warranted the full works.

Brits just like shooting. The Air Rifle scene took off in the 80's. Shooters demanded more. The factory offerings just weren't enough. Much credit must be given to the few custom shops like Mastersport and Venom in catering for the new enthusiasm. We have better factory rifles now because of their work.
I think these examples are important to the history of arms. So few were made. Its amazing these custom works found enough business, couldn't have been easy. Examples may be difficult to obtain as many are already rightly in collections but I still don't think the prices reflect their importance. Barely reflect the work that was put into them.
On pure gunsmithing they are interesting and nothing completely impossible, just the tuning of the base factory. The tuning made developed. So there is a limit to what worth, but I don't think the actual value has been reached yet. I don't think their importance has been fully recognised either.
They are the last horrah of the spring rifle. Cherish them for their piece of history.