There seems to be some confusion in terminology, and I get the impression that the OP's dealer may be calling all M1890s "gallery guns" which they certainly are not. In fact probably only 5% or less were true gallery guns, and like whiz-bang stated, all of these were chambered for .22 shorts only. I cannot imagine any gallery gun being chambered for .22 WRF, the forerunner of the .22 Winchester Magnum (in reality just a longer version of the .22 WRF with higher pressure).
Also, all M1890s were caliber specific, i.e. they could only work properly with either .22 short or .22 long or .22 WRF, or after 1919, .22 long rifle and never interchangeably. Since the .22WRF uses a larger diameter case than the others, it's never a good idea to try to fire any of the others in a rifle chambered for it, although they will chamber.
The very similar M1906 would allow for cartridge interchangeability (.22 S,L, or LR) starting in 1907 and was the first Winchester model to be chambered for the long rifle cartridge.