Lighter shaft, I'm over 17% with 50gr inserts and 125gr broadheads with nockturnals and ff sk300 vanes, I go over 19% just switching to Easton microlite nocks....but none of that possible without a lighter shaft. Ditch tail weight, no wraps, switch to Easton microlite nocks, 125gr broadheads is quick way to start. My shafts r speedpro 6.2 gpi, total arrow weight 389gr at 28", I get it all, speed, enough weight, and crazy foc, but the biggest factor to start with IMO is start with the shaft. Stay low to mid 8 gpi on 70 lb set ups and 125's up front, don't get carried away out back. On the hooter shooter out of my specialist 70lb my 6 arrows did a 3/4" group at 20 yrds right out of the gate, twisting a couple nocks brought it to 1/2", the shop was impressed and only saw maybe one setup in for a supertune do an initial group that tight or better before nock tuning, so seems I've stumbled upon a good thing in my arrow building quest. Heavier the shaft the heavier u have to go up front so it's easier to start with lighter shafts to get the flexibility in components and even just to have over 10% with a 100gr head.