I am a new owner of a CZ 550 in 6.5X55.

I was astounded to discover how long the throat was in this rifle. With a 130 grain Hornady Interbond loaded as long as reasonably possible there was two tenths of an inch to the lands!

I have ordered a custom reamer to have the chamber brought to a match style of throat, ie very little!

So whatever you get I would verify the chamber dimensions first. The 6.5X55 by CZ was apparently cut to the old Mauser spec so you could shoot 160 grain bullets and not force them into the lands and blow yourself up.