I just re-read your original post, Jorge, and I see you note specifically the No.1 Mk 1. I am not sufficiently familiar with Lee Enfields to know if there is a difference in those early versions from say the No.4 Mk 2. I assume that since they all shoot the .303 British cartridge, there is no significant difference in their bolt faces or feeding from magazine.

Paul

Remember that BSA made and offered commercially Lee Speeds "Enfields" in 0.315 bore this was the old Austro-Hungarian 8x50R cartridge for use on the Indian Sub Continent where the 303 was banned as they doscovered that the Indians just could not be trusted ................................. how strange!!!

    Hence we know that the 8x50R will work so one can be fairly sure that the 8x56R which was the updated 8x50R cartridge will work in the Lee Enfields.

    Then of course Ken Waters had a commercially produced Lee Enfield No1 converted to  a .375 wildcat. The rifle was originally an .375-303 Accelerated Express by Westley Richards but the bore was badly eroded by cordite. Ken made the cartridge based on Marlin 444 brass necked down to hold .375" bullets. Cartidge dimensions are to be found on page 188 in  the book :-

"Big Bore Rifles and Cartridges" by Wolfe.

      Velocity is not high are around 2050-2200 fps but then I would not want to be hit by any of the bullets from it   .

Thanks for the info guys.