I picked up another matching No4Mk1 recently, the receiver, magazine and bolt all have the same serial numbers.
It shoots straight with handloaded 174 grainers, but about 4 inches high at 50 yds, I know to use a 6 o'clock hold with these loads.
It started out as an ROF rifle and went through the FTR program, it has what looks like Savage walnut wood with an alloy buttplate with FR stamped in the stock and a letter S on the upper band and fore wood metal. The rear micrometer sight appears to have been changed as well and has a letter B on the top, perhaps a BSA.
The FTR is stamped in small letters on the left wrist along with England and has the usual BNP stamp on the receiver round, the 2.222, 18.5 Tons etc, stampings are on the muzzle end of the two grooved barrel.
So, it appears I have a conglomerate of parts from all over the globe going into making one rifle, I love Enfield rifles.