Thanks, BR.
I am familiar with some of the 1917 Enfield history, have read it was to be originally a 7 MM somewhere between the '06 and 7mm Remington Mag without a belt. The great war was looming so a decision to chamber it in 303 was made to prevent having a cartridge change was made. My father's has a .311 barrel and mine was rebarreled in WW2 with a 2 land Johnson Automatics barrel. I have never seen a drawing or a photo of the intended 7mm. In the early 50s the Brits were still trying for a 7mm but with a smaller case during the NATO trials.
Incidentally my Enfield with the 2 land barrel shoots a 1/2 high by 1 1/2 wide group with  a 4 power Weaver and no accurizing of any kind. different loads seem to make no difference.
I am almost finished with setting the barrel back to cover a bad spot in the chamber on my father's. I am going to ream the neck and throat for 303 bullet and see which of the 2 shoots best. The other has a 6.5mm barrel waiting for it.