Was it a matter of timing? Had the .22 LR not been developed by the time the mid-caliber, so called rook rifles were in demand
I believe you are correct in your last statements.
As many as 40 of us gathered from 2000-2010 to shoot them annually near Cincinnati. Tom Rowe & I restarted Rook Matches last fall, in E. Tenn. along with SS Sporting Rifles. Another match next month - posted on this forum.
Many Rook rifles were bored out to .410 in the 1920’s with the UK ban on rifles.
Tranter was a big supplier of actions to the trade.
Seems the most popular cartridge found are:
250-295
.295 / 300 Rook
.360 No.5 / .380
Sorry, I haven’t taken the time to learn how to post photos on this forum. But, I do have a ‘19th Century Battery’ FB page to communicate my match, with lots of photos.
You should acquire one as they are fantastic little rifles and fun to shoot.
