I currently shoot a Drenalin with 70lb limbs maxed out with 28dl. My arrows are 28" long also. I took my bow to shop to have them attach the rest cord and serve it in. I also had them paper tune it. I bought then bought some Gold tip Expidition arrows. When I looked on the box it tells me to shoot a 5575 (400)arrow. When I look on Gold tip website it tells me I need a group 5 arrow which is a 7595 (340) arrow. I dont know if the chart is wrong on the box or what. When I look on Easton, and Carbon express it tells me I need a .340 spine. I dont know if gold tip arrows are built different or if the chart is just wrong on the box. I shot through paper to see how it shoots, and I had a left tear. I put on 85 grain tip and still a tear. I then backed off limbs about 4 turns, and 75 grain tip to get bullet hole tear. Do you think if the shop tuned my bow with .340 spine arrow, and I am shooting .400 it that the reason for tear, or is my spine just too weak for bow. I dont know if I should adjust rest to get bullet hole, or get more rigid spine arrows. I bought bow used so I dont know if it specifies in manual what spine to shoot. It just seems weird that gold tip numbers just dont jive. If I do need stiffer spine I will be pretty upset since my arrows are new, and I just went off chart on the box. I am pretty new to archery so I dont know if I am just reading too much, or if I have a problem. Any input is appreciated.