IMO, most of the advice that you've gotten on here is good. Again, you don't need speed, you need energy. Speed (e.g. higher draw weight) gets you more energy, but can be substituted for mass (e.g. heavier arrow set up). Another thing that is a factor at lower speeds is mechanical advantage of the broadhead. There is a reason you usually see single-bevel 2-blade broadheads on traditional setups. They get the best penetration and are less affected by ribs, or glances off of bone. You want a long blade with a gradual angle, and preferably a cut-on-contact. If you do get a broadhead with a ferrule, try to make sure the ferrule diameter is greater than the diameter of the arrow shaft. Here are 12 good things to remember (I poached this from the internet):
Quoting and paraphrasing Dr. Ashby's twelve factors, they are listed in the order of importance that he has assigned:
1. “Structural Integrity of the entire arrow system is the most important factor. It applies to every aspect of the arrow, from the broadhead tip and edge strength to the nock”.
2. Arrow Flight is number two in importance. ”You should spare neither effort nor expense in achieving absolute perfect arrow flight.”
3. A higher FOC is important. The degree of arrow forward of center ( FOC) makes a big difference. “Above 19 % the penetration gain continues increases as FOC increases”.
4. A higher Mechanical Advantage is important. The higher the mechanical advantage of the broadhead the more pronounced effect it has on penetration.
5. Shaft-Diameter to Ferrule-Diameter Ratio can be critical. The diameter of the broadhead should be larger than the arrow shaft
6. Arrow Mass or arrow weight is important. ”You should use the heaviest arrow acceptable trajectory allows.”
7. Broadheads should be Shaving Sharp. A smooth sharp edge is better than a serrated edge.
8. When considering Shaft Profile, tapered shafts have an advantage.
9. A smooth Broadhead With No Bumps to impede penetration is desirable. ”How gradually and smoothly the broadheads ferrule fades into the blade becomes a major penetration factor when heavy bone is hit.”
10. The Type of Edge Bevel is important.”When broadheads, identical in all aspects except edge-bevel, are tested side by side on identical arrows, single-bevel versions demonstrate penetration increases in 100% of cases involving bone impact”
11. When discussing Tip Design Dr. Ashby believes “the Tanto shows the best performance”
12. Arrow Mass or weight probably has little effect in soft tissue. However, there is a significance difference if bone is encountered.
