Williams’ floating chamber was also used in the Colt Conversion Unit, it replaced the slide/barrel, etc., of the M1911A1 pistol and when installed, the user could fire .22LR cartridges with the approximate recoil effect of the .45ACP cartridge. I bought one new in 1975 through the gun shop I worked at for the princely sum of $69 + tax...
Colt Ace floating chamber .22 kits have gone out of sight like everything Colt (see American Rifleman on Colt `snake’ revolvers). FWIW I bought a Remington WWII M1911A1 in 1975 for $125.
I recently bought for a reasonable price a Colt Ace II .22 conversion kit; haven’t fired it yet. Much simpler design with an alloy slide & one piece barrel. Comes with a mainspring housing & spring but I can’t tell the difference with the original.
As for Garands, I bought a new receiver in 1998 & one of those all but receiver kits. Put it all together & it shoots fine.