WWII Pacific USMC Snipers

[cplstevennorton]

Could this be a snipers field mod in putting a groove in there as a personal thing in the last pic it gives the impression of there being a shallow groove that starts about and inch from the rear band.
Or are field mods not allowed due to what may be perceived as damaging military equipment.
Just asking!

I've never found any evidence of the Marines doing that. But the Marines did modify weapons. For Example you see evidence of pistol grips added to fore-grip of the BAR.