I believe some of the issue (if there is any of measure) with the Enfield was a combination of manufacturing tolerances both within Britain at the time as well as across the Empire (or what was left of it). Much like Garands or M1 Carbines here, there are certain manufacturers that have a reputation for producing slightly better examples than others. Don’t forget as well that while Stateside, the folks that made Garands went home after their shift to their homes, the folks at Maltby went home to Heinkels and Messerschmitts. The British doctrine at the time revolved around the use of stripper clips. The thought of separating the magazine from the gun was relatively unheard of. The typical British soldier had gear that was designed to support the Bren, and the fact that he carried an Enfield was kinda secondary.
Sorry for the tangent and (politely intended) rant. I’m a bit of an Enfield nerd.