no offense but if the lcr couldnt handle the fbi load, its well not safe to shoot. i believe it was proven with the kframe 357 that the fbi load is safer on a gun structurally then the fireball/atomic 110-125 grain loads that replaced it for police duty.
either way, get a box of ammo and range use it. if it DOES hurt the gun, i think ruger would send you a gi foot locker full of redhawks as consolation. seriously its ok.