Grizzly Broadheads~ Bevels ?

[Carcajou]

thanks for the input! great info!

[Daddy Bear]

If right bevel Grizzly matched with left wing fletching was all you had on hand, then so be it.  But, if going out of the way to do so, by creating some obscure scientific experiment, that makes no sense at all.  The arrow has a limited amount of energy, and to expend any amount of this value by spinning the arrow against the mechanics of cutting rotation, to no purpose, is needless.  All the penetration testing has shown many worthwhile techniques and methods to enhance this single bevel cutting, and I do believe matching arrow rotation in flight, to some degree, is a positive to the equation, not a negative.

Best  

[JimB]

If you read the Ashby reports,it was tested and he found that the single bevels out penetrated double bevels but when the single bevel was used with mismatched fletch,the double bevels penetrated better.

I know people who have killed game with single bevels and mismatched fletch and it isn't that they won't kill and probably will pass through,depending on the setup but why set up an arrow to penetrate less?

[Retnuh Wob]

I had the understanding from the literature that what you wanted was a helical fletch that rotated the arrow in the same direction that the broadhead bevel wanted to rotate the arrow during penetration. However, I just listened to a 2013 presentation in Texas  by Dr. Ed Ashby.  In the section on tuning EFOC and UEFOC arrows with Grizzlys he recommended straight fletching with no helical.  I was surprised by this, and he did not comment on the reasons why.  He did comment though, on a document on tuning these done by Todd Breeding, I believe. He stressed that author used a helical fletch only because he only had a right helical clamp at the time.

[ChuckC]

Probably because even if it is spinning in the correct direction, it is spinning at a different speed, so it would have to slow down or speed up anyway. He is likely thinking to let the broadhead work at its own pace and direction without adding any hinderance to it.  As stated above, this probably will not change anything on a deer shot.

ChuckC

[ranger 3]

Interesting thread, I want more

[Daddy Bear]

I've been using the Grizzly heads for near as long as they've been marketed.  Though I've not used the latest incarnation, I've used every generation of the head going back to samples my Dad purchased from Elburg.  My second favorite is the Hill, they share a similar profile, fly identical from my bows, work well on game, and have a ton of nostalgic appeal.  The deer on the left was arrowed with the Hill, the deer on the right with the Grizzly.


Though they both work well, the Elburg head holds up to more use and abuse before giving up the ghost.  The ferrule/pin design of the Hill tends to fail long before the Grizzly.


The single bevel design adapted by Elburg is no joke.  With proper material and hardness to hold an edge, it is impossible to duplicate the degree of sharpness with a double bevel, for the simple reason that the edge angle on the single bevel is lower and thinner.  No matter how sharp, the edge angle on the double bevel is higher and fatter.  My single bevels not only shave hair, they shave tiny curls off a single strand of hair.


As for the rotation, a single bevel walks and cleaves through the cut due to the mechanics of the design.  On the Elburg head, it walks and cleave the cut in the direction of the bevel rotation.  Hence, the S-shaped of the entrance wounds you see through hide and flesh.  This is an exit wound that is cleaved open.  Though the upper corner of the cut is clogged with fat, the remainder of the exit wound is wide open and allowed a strong blood flow.


The advantage you see on deer size game is the very reason Harry Elburg invented the Grizzly many decades ago. Elburg stalked deer on foot with a flat bow. His favorite shot was from the deer's blind spot shooting a steep quartering away angle from behind the onside shoulder into the offside shoulder. He designed the Grizzly to maximize bone penetration to increase the odds that the arrow would penetrate the offside shoulder giving you two holes for more damage and blood loss. This is an example of the single bevel rotational design in how it splits and penetrates bone going completely through an offside shoulder when using a low powered longbow.

With all that said, as much a fan I am of the original Grizzly design, I still use the more fragile Hill head for pure joy of nostalgia.  I imagine that many have their own personal favorites for a plethora of reasons, regardless how well they may, or may not, stand up to maximum abuse.  But, for maximum penetration on large game, a good single bevel can be a solid positive to the overall equation.

Best  

[TxAg]

I love the pics above. I had these and thought I'd share...

53@29 "Hill" style bow from 15 yds using a 515 gr arrow. It passed all the way through.



The "S" shape cut