Dad's friend has a 700 chambered in 7mm mag that extracts and ejects shells fine when you cycle the bolt by hand but after firing the rifle the bolt has to be pounded back and out to remove the case- its sound similar to high pressure signs but various ammunition has been tried and the primers look fine. Seems to be some brass shavings around the bolt face when you finally get the case out. Is the chamber cut wrong in this rifle or does anyone have any other theories as to why the problem occurs?

Hard opening and extraction sounds like excessive headspace.
No flattened primers though, strange.

Definitely sounds like excessive HS. Get it checked before you shoot again. Charles.