I have a question after reading a post on another site.  If you have a m77 mkII in say .338 wm and wanted to convert to .375 Ruger, .416 Ruger or .458 WM could you use an original stock made for a long action ruger.  With the barrel change would the new barrel fit in the old stock?  The caliber change should be very simple, however the stock is my question.  I have a stainless .338 in a synthetic stock that I would like to use as the starter. My idea would be a slim, trim .375, .416 or .458.  Any ideas? Thanks.