Yes my 375ex action is not machined for the the mag cut off either, is there a small groove at the back near the bolt handle for where a dust cover would have cliped in ?

Strangely had this & not on others of the later BSA pattern, also very very few of these put together by other makers, very few with just there name added .

Notice the saftey has the BSA PAT but not BSA engraved, as nearly all the others with this safety have ?

Very interesting !