Thread: 222, Bsa

So i have sort of found, looking a , being offered a BSA in .222, not sure of the model and don't know a lot about them.
This ones maybe done some work, or the original barrel is buggered from rust , corrosive ammo, bad storage....... I don't know.
The wood work is surprisingly good and the bolt looks very good and action smooth.
It has being re-barrelled with a Gunworks stainless barrel ( I think, not Hardy's ).
The thing that to me as someone know doesn't know much about them is it has a what looks like a drop out mag .
Looks old school like the gun, is this original , normal or some home / gun smith engineering ?