The new production Grizzly BH's are being supplied with an angle of about 26 degrees. That's means A LOT less work is required when 'setting the edge' than on the older ones.
During penetration, it takes very good quality steel with a fairly high Rockwell hardness to HOLD the thin edge I prefer, but a broadhead that CAN hold that edge cuts with greater ease, and less resistance. The 190 Grizzly does that. All the 190's I've had tested have run between R52 to R55. That includes ones made by Harry Elburg, Jim Able as well as those of current production.
The data leaves no doubt. Because of the rotation induced, single bevel BH's commonly cause large bone splits (almost to the point that I could say 'routinely'). Double bevel BH's simply do not cause bone splits. I've observed not even a single example during all testing. To penetrate a bone, a double bevel BH must either cut the bone, or force its way through. That requires expendature of more of the arrow's (limited) force.
ON A BARE SHAFT, the modified 190 Grizzly (1" wide) makes one complete revolution in 15 3/8" of tissue penetration - a 'rotational rate' that is almost four times as fast as that of an arrow in flight. The arrow's rotation actually accelerates after tissue impact. During bone penetration, the BH/arrow rotation applies a significant 'torque force' on the bone, tending to cause large bone splits and allowing easier passage of the broadhead and shaft through the bone. Single bevels BH's are worth the effort required.
If fletching induced rotation and bevel induced rotation don't match, the arrow's rotation not only has to stop and reverse on impact, it has to ACCELERATE in the opposite direction (using up a lot of that precious 'limited energy'). That's why it's so important to match directions of rotation of fletching and BH bevel.
Grizzly = right bevel. Use right wing feathers.
Abowyer Custom = Left bevel. Use left wing.
Cheetah and Outback are available with either right OR left single bevel edges, as well as double bevel versions.
Ed