In 2006 we were introduced to Dr. Ed Ashby by the custom bowyer OL Adcock. After our first meeting, we really started diving into Doc's arrow lethality research. Like so many other bowhunters who read Doc's research for the first time - we had an "Aha Moment."

Dr. Ashby's research touched on so many things we already kind of intuitively knew but also explained so many concepts we had never thought of. Since that time, GrizzlyStik has obsessively addressed and built each of Dr. Ashby's top 12 arrow penetration factors into our systems.

These 12 arrow penetration factors were strenuously researched, tested, and ranked in order of importance by Dr. Ashby. All 12 points are insights gained from Dr. Ashby's 30 years of empirical bowhunting research. (Note that #10 - Edge Bevel - jumps up to near the top of the list if a bone is encountered.)

Since 2007, GrizzlyStik has been obsessively researching, building, and refining each of Dr. Ashby's 12 points into all of our arrow and broadhead systems. No one point is the silver bullet for arrow penetration. Each point enhances the next point until you reach a compounding effect of arrow penetration.

Ashby Rule #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.

GrizzlyStik broadheads are tempered to eliminate tip curling and broadhead twisting. Our Ashby is made for ultimate strength and durability. GrizzlyStik tapered carbon arrows are made with our Mitsubishi 3K woven carbon cloth to eliminate any weak spots. They're thickest and strongest right behind the head, exactly where most other carbon arrows fail.

Ashby Rule #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 what the cost. Pay close attention to the other factors too though or you may find yourself shooting arrows that fly perfectly but can't penetrate well at all.

GrizzlyStiks are the ONLY full-length tapered carbon arrow available. Our full-length taper recovers from the archer's paradox faster than any parallel arrow AND upon impact, the stiff front end resists bending and drives the broadhead through whatever gets in its way

Broken Moose scapula from Single Bevel Broadhead

Ashby Rule #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 enhance penetration from 40% to 60+%.

The full-length taper of GrizzlyStik carbon arrows builds in EFOC and with our brass inserts, insert accessory weights, and broadheads up to 315 grains, you can customize your FOC to suit your own needs.

Ashby Rule #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.

Our Ashby broadhead is designed as close to the 3:1 ratio as strength and durability would allow. It has the highest mechanical advantage of any GrizzlyStik broadhead with the heavier Samurai series broadheads following close behind.

GrizzlyStik Maasai 125 Single Bevel Broadhead Elk Penetration

Ashby Rule #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.

GrizzlyStik arrows are equal to or less than the diameter of all the GrizzlyStik broadhead ferrules.

Ashby Rule #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.

The GrizzlyStik system of heavy full-length tapered carbon arrows and broadheads up to 350 grains allows you to customize your arrow to reach your target mass weight for optimum penetration.