Are you using a fast flight string material? I used them with a recurve tht pulled 48# cut to 29" with 150 up front and they were too stiff. I found 500 to be better but still not right and far too weak. Also, keep in mind the skinniness of the arrow brings it closer to center which stiffens the spine as well, if I had to guess, assuming you're using low stretch string materials, I would do what cyred4d suggests and have access to bump the front weight as well. If you can get 275 up front, it will put you into efoc and should greatly help penetration and accuracy. They are great arrows, but a little finicky.