No idea on inlet but I have several browns marked that way on the end. Profile looks pretty brownish too.
The front screw going up thru the recoil lug says Vanguard to me.
MKV. Vanguard has the tang inlet down into the stock.
Seems a bit on the heavier side for a Wildcat.
Not a Wildcat, they are not marked on the buttplate area. Neither were the Basners I used 10 years ago (so might have changed).
As TheKid pointed out, Mk5 and probably a Brown Precision.
Brown. I have the same stock sitting in front of me, albeit for a Howa.