I am currently shooting Black Eagle Renegades at 27.5" with 300 spine at 70lbs. Current arrow weight is around 475 grains. I am looking at adding some of the brass insert weights to increase FOC and overall weight. I am looking at bumping total arrow weight as high as I can without increasing arrow spine. I already have half a dozen new arrows that I going to build. Ideally, I would like to get to arrow 550 grains if I can without having to go to a stiffer spine. A couple of questions: 1) Is there a way to calculate how much of a weight increase I can make without needing to go to a 250 spine? 2) How the brass inserts installed? I can see that they need to be installed before installing the insert but, how is that done? I am assume it is a simple process but I have been unable to find any instructions on how to do it. 3) Is it possible to add weights to my already built arrows if I like the final build on the new arrows?