Dr. Ashby’s reports and articles are graciously compiled and published free of charge by the folks at Alaska Bowhunting Supply and are readily available to anyone that visits their website. These reports are a wealth of knowledge and represent some of the most in-depth field testing the archery world has ever seen. We are very grateful to ABS for allowing us to re-publish some of this incredibly in-depth content. The following list was Adapted from the Dr. Ed Ashby’s “Terminal Arrow Performance” seminar.
Dr. Ed Ashby allowed Alaska Bowhunting Supply to use his name on their broadheads with one condition. He insisted that ABS make it clear he receives no compensation for the use of his name whatsoever.
These 12 arrow penetration factors were strenuously researched, tested and ranked in order of importance by Dr. Ashby. All 12 insights were gained from Dr. Ashby’s 30 years of empirical bowhunting research. Note that #10 – Edge Bevel – jumps to near the top of the list if bone is encountered. Read Busting Bone in the August 2015 issue of the JOMH for more on the science behind bone splitting.
1. Structural Integrity
The most important factor of arrow penetration is structural integrity. If any component of your arrow fails penetration either completely stops or is greatly reduced.
2. Arrow Flight
If an arrow is not flying perfectly it’s wasting valuable energy that could have contributed to penetration. If an arrow impacts before it has achieved perfect flight, energy is wasted that could have contributed to forward momentum and penetration. Perfect flight is crucial. You must achieve it no matter the cost. Pay close attention to the other factors however or you may find yourself shooting arrows that fly perfectly but can’t penetrate well at all.
3. Arrow FOC (Forward of Center)
Tests have shown that EFOC, defined as 19% – 30% forward of center and Ultra EFOC, defined as over 30% forward of center enhances penetration from 40% to 60+%.
4. Broadhead Mechanical Advantage
Long narrow broadheads have an advantage over shorter wider heads. It takes less energy to push them through an animal. That is their mechanical advantage. This is second only to EFOC and Ultra EFOC as a penetration enhancing factor.
5. Shaft Diameter to Ferrule Diameter Ratio
You’ll lose up to 30% of your penetration potential if the shaft is larger than the ferrule where they meet. It’s best to be slightly smaller in diameter than the ferrule of the broadhead.
6. Arrow Mass or Weight
Heavier arrows absorb more energy from the bow at the shot & they carry their momentum better than lighter arrows so they penetrate better. Bowhunters should use the heaviest arrow that will deliver a trajectory they can live with.
7. Broadhead Edge Finish
Broadhead edges that have been honed and stropped smooth have a 26% advantage over smooth filed edges and a 60% advantage over the coarse “serrated” Howard Hill edge.
8. Shaft Profile
On all shots tapered shafts show an 8% penetration gain over parallel shafts and a 15% gain over barrel tapered shafts.
9. Broadhead/Arrow Silhouette
Smooth transitions and slick arrow finishes greatly enhance the penetration potential of your broadhead/arrow combination. Broadhead ferrules with bumps or any irregular surfaces impede penetration, especially in bone.
10. Type of Edge Bevel
Only if no bone is encountered does this factor rank 10th. If bone is hit, and it often is, this factor jumps up toward the top of the list. If you can’t get through the bone, penetration stops. The powerful rotational force of single bevel broadheads splits bone. Single bevel broadheads regularly turn what would be a wound into a killing shot. Note: Your arrow must be of sufficient weight and strength to drive the broadhead through and withstand the forces involved in breaching the bone.
11. Tip Design
In all testing where bone was encountered the Tanto tip performed best. It resisted damage and skipped less than any other tip design.
12. Arrow Mass 650 and Above
When soft tissue is hit, this factor is ranked last in importance BUT if heavy bone is hit it will be near the top of the list. Heavy bone is almost impossible to breach unless you have 650 grains or better in mass arrow weight.
GrizzlyStik broadheads and arrows were engineered from the ground up to meet Dr. Ashby’s stringent and tested criteria and to perform under the toughest possible field conditions. For more information on the GrizzlyStik system visit their website at www.grizzlystik.com or this video on YouTube.