Re: mark 5 action
I have one as well but can not find any my pictures.
Like other have said, yes they can be built on and if the gunsmith starts talking bad, just move on. Would it be my first choice, NO.
If you have a action already, then building off it is fine. The 60 degree bolt, the smoothness can not be beat. But if your looking to find a action to build on, then just by a custom action. MKV are usually expensive to buy and for the price you can get a nice custom.
Mine is on its third barrel in 18 years. I purchased it for myself when i was 14. It has sentimental value now and has never shot better (.33 moa).