I recently purchased my first Enfield, it is a No4 MKI (F) dated 11/48 PF616XX.
I was wondering about the grooves on the upper handguard (which seem to improve grip) and had not seen them anywhere until I came across a post here with a photo from madcratebuilder, which has the same grooves.
(Mine is not a sniper)
I thought they were some bubba job, but now I am not sure, and I thought someone might tell me which units these appeared on?