.22RF trainer details wanted

[Tony Smith]

Have recently acquired a Lithgow SMLE No2 .22 trainer. Lovely bit of workmanship, and cheap to run. .22 ammo is available these days in a bewildering array of choices, but what were the original specs of WD .22RF ammo? .22 trainers have been in Commonwealth use since before 1900 (with a Morris Tube), and are still in use today (in the Aust F88T .22 trainer). I would presume that the original .22 used was a .22 short, but currently a .22LR is used. What were the original specs (Short/Long Rifle, grain weight, and MV)? At what point did they change from a .22 short or .22 long (rifle will chamber both)?