What do you guys do to figure out arrow weight? Say if i wanted to buy a Beman ICS hunter arrow which is at 8.4 grains per inch and i want it trimed down to 27 inches. I assume you multiply 8.4 times 27 and get 227 then add 100 for the field point to get 327. How much would i add to 327for blazer vanes and a nock point to find my total arrow weight?