Hi , my martini is in .223 Rem uses a take off Winch  Ranger barrel made the scope  mount , I have put  a plate between the action and barrel  held as in Rem reciol lug ..
In my maratini it holds a bar from which the forend is suspsended so the barrel is truly free floating.. 
Shoots in the low threes mostly , sometimes gets to the low ,2's never over.5 , sure is   hell on rabbits..Rob