Surpmil
Would you believe a book printed by the British War Office?
I looked for a good while but could find the section on proof testing the Enfield rifle BUT it is in this book. You should read this book that way you wont have a problem when I quote from it.
Page 360 of The Textbook of Small Arms.
From Jim Sweets "Competitive Rifle Shooting" first published in 1946.
I have a modest collection of Enfield Rifles, BUT I have a very large collection of manuals for the Enfield rifle and none of them are considered science fiction.