The Model 1890 and the .22WRF were introduced as a pair.
The WRF casing is enough larger in diameter that regular 22LR would often split when fired in the WRF chamber.
The ammo was made in Canada by CIL up until the takeover by IVI in 1968, at which point it was delisted and has not be available here since then. IVI delisted a whole bunch of old RF calibres at that time, including .22BB, .22CB, .22 Shot, .25RF, .25 Stevens, .32 Short, .32 Long, .38 Short, .38 Long. Personally, I will never forgive them for delisting the .25 Sevens: it works so nicely in my Cooey Canuck!
The .22WRF ammo was much more expensive than rgular .22RF stuff, enough so that sales of the rifles, after a good start, fell off rapidly. The 1890 Model was revamped for regular .22LR ammo and became the Model 1906. They then made a zillion more rifles.
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