I've had hundreds of ROF Fazakerley No.4Mk.2 rifles but never one stained like that. I'm just referring to my experiences. Nothing is set in stone when it comes to these rifles. The L81 rear sights were sold by SARCO under false advertising pretenses and it's really unfortunate that folks have permanently altered rifles by drilling holes in the receiver. Especially when the correct target sights are available if one keeps an eye out. The axis pin holes can be sleeved with tubing soldered in and the hole in the side for the detent filled with steel filled epoxy and touched up. My uneducated guess is this is just one of the new Mk.2 rifles that was worked on by a previous civilian shooter.