There is a lot of mis-information out there about the FR series and the Spanish rilfes (and many other imported military arms). I try to exercise common sense. If the small ring action (FR-7) was intended for lower pressure ammo (7X57), I will keep the pressures down. If I want a rifle to shoot full power ammo, I will buy a modern rifle.
You must always consider these were built on used receivers. I don't think any of the FR's have a receiver any newer than the mid 40's. You have no idea of the round count. You have no idea how well it was heat treated. Be safe, have it checked by a competent gunsmith. This advise I would offer for ANY pre-1950 arm or any milsurp weapon.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball