Just to clarify a few points from an Enfield-o-phile...
A Jungle Carbine is a No5MkI rifle. Wandering zero is a myth, propagated by British troops becuase they were envious of American Garands, and wanted new rifles in the 50's.
A NoI rifle is a SMLE... No4 and No5 rifles are not. If anyone does see a No1MkV, please buy it for me, as there were only about 20,000 of them made as intermediate troop trials rifles between the World Wars - A step between the No1 and No4 rifles.
A No4 rifle was rated as being "effective" to 550 yards by the Canadian Army, in the hands of the average soldier, aiming at man-sized targets (as is common in battle, I am told).
I would suspect that the effective range of the rifle has a lot more to do with who is behind the trigger, rather than the particular firearm in question. For me, thus, effective range of the No5 would be about 100 yards!
I will, however, happily put my No4Mk2 up against any old Remchester in 7mmSupershortmansyndromemagnum on the target range, any day!
Flame suit on - Danger close: Fire for effect!
Neal