Hello Neale,

congratulation for your rifle!
I would strongly recommend to change the Brno safety to a 3-position safety type Win 70.

My rifle has feeding problems with all sort of bullets which are not round-nose shaped.
(magnum length action and the short .458 Win. round do not work together very good)
Steve Zihn recommended to break all sharp edges of the chamber, maybe that helps.

best regards
Rolf