Thanks, thegreg.
Your figure of 1 in 15 may well be right.
In the immediate post-war years, lead was briefly a controlled strategic material, not for use in such trivial things as airguns. Even when that restriction was lifted, the country was bankrupt, and times were hard. Perhaps explaining why the early Webley MkIII was mostly made in .177”, as the ammo was cheaper.
Definitely the case that U.K. market airguns (including imports like Diana/Original and mid-range guns like Meteors and Webley Falcons) from the 50s through 70s are much easier to find in .22”.
I suspect that the arrival of AGW in the 70s may actually have increased the market for .22”. Their articles were full of phrases like “full power”, “man’s gun”, “knock-down power” (ugh...). All the hunting writers used .22”. Arthur, JD, etc.
Oddly, Webley MkIIIs are not too hard to find in .177” (though the majority are .22”), probably easier than Meteors or similar. Theory: they were used for bell target and nascent 6 yard and 10M match.
.20” and .25” are in a different league. Basically, the commercial idea behind both is to persuade committed shooters to buy another gun. .177” v .22” is a mass market decision, many of whose buyers will not buy another gun, at least not for years. The marketing assumption behind the niche calibres is that enthusiasts will buy them, because they are different and interesting.
If you doubt that, the American domestic civilian firearm market operates principally not on the model of selling guns to people who don’t own guns, but on the basis of selling more and more slightly different guns to people who already own guns.
Ditto here with the niche calibres. I do not gamble, but if I did, I would wager that absolutely no one buys a .20” or .25” as a first gun. They are things that only established enthusiasts buy.
As evidence of which, I have three .20” guns. And more than one tin of .25” pellets, bought just in case I buy a .25”.