FMJ's can bend too...a few grains will not be noticed by 90% of shooters, spine however will affect groups far more. Going to the shooting and numbering arrows system is still the easiest way to findout what you have. My Goldtip Kinentics are all within a gr or less. Even after fletching, even though I shoot the higher grade ones, I still shoot the the entire Dozen to see if I have any flyers! Ones that won't group well. Take these out of your hunting arrows. I have done this for years and only ever had to take out two arrows that would not group well enough to shoot with. A bigger problem is most arrows start breaking down in spine if you shoot a lot.
I have arrows that have no physical signs of wear, but after a couple thousand shots...have to be tossed. This is if you shoot 7,000 to 10,000 shots a year. I have averaged about 7-10 thousand shots for the last 6 years. Never had an arrow blow up on my bow doing this and flex testing too. You can't do this with FMJ's either, but FMJ's can still blow up. If you get one flying on your groups, get rid of it...good sign it is breaking down and may blow up...at worst you end up with an arrow in you forearm...at best..you do the equal of dry firing your bow.
Sorry...you guys brought to mine some other thoughts