There are some hard heads out there who want to insist that you can't inter mix the 2 because bad things will happen, but the difference in specs are well within the tolerance of SAAMI or CIP. The proof pressures are the same. I have shot several thousand "NATO" cartridges from stock Savages and Remingtons with no problems whatsoever. I find it pointless to debate these small differences with someone who wants to pick fly scat out of the pepper.
One thing I DO NOT recommend is shooting lacquer coated steel cased ammo, commonly from Russia or eastern block countries.