well here's my two cents worth, i've been shooting less than 50# for over 12yrs. didn't know about foc, or gpi. i've shot magnus, bear, and steelforce in two blade sometime with bleeder blades, sometime without. killed over 28 deer and two bears and only had maybe two pass throughs. only had one that went over 50 yrds. some may not agree, but i believe they dance around inside. when field dressed there organs are nothing but mush. most go less than 30yds. i'm certianly no expert, i do AGREE, razor sharp blades