Thanks for weighing in Ed.  It's interesting that the bevel on the tanto, when cut on the same side as the blade edge, doesn't seem to work as well as the bevel being cut from the other side.  Logic would seem to dictate that the point bevel on the same plane with the blade bevel would complement each other.  That's why we test things, huh.

I agree re your assessment of the Zwickeys.  I've been shooting them for more than 30 years.  They're an excellent head, and I applaud Zwickey for being among the first to offer a blade that is mostly single bevel.  I'm hoping they'll modify the design a little so one can run/sharpen the single bevel the entire length of the blade.  Making it thicker and heavier, which would enable more surface area for the bevel would also be nice.

Jerry, the reason having the Tanto's bevel on the same side as the edge bevel doesn't work as well is that it results in more bone-skids, redirecting the arrow's direction of rotation.

It appears to be much like a rotating top, which tends to spin away from any solid object it impacts. Single-beveled on the reverse side doesn't seem to do this as badly, because BH rotation is reverse of that of the tip's bevel. I'm leaning towards a double-bevel on the Tanto as being best, but still don't have any result differences that are conclusive. Hope to after this year.

You might chack with ArtB. He was having penetration deviation problems with the single bevel on same side as edge bevel. Changing it cured the problem.

Ed
TGMM Family of the Bow

Ed,

You're saying the Tanto tip should be double bevel, while the rest of the Grizzly edge is single bevel?

Jason

Jason,

That's one of the configurations still being tested. The other is to single-bevel the Tanto tip on the side opposite the edge's single-bevel. It's when both are on the same side (for that half of the blade) that the tendency to spin-off a bone surface begins to show up.

The difference is of little consequence on rib hits on open-rib animals. There, the BH just slips off the rib to enter at the next intercostal space. However, it can be a problem on bones with larger flat surfaces, such as a scapula, or on highly curved bones, where redirection of the arrow's path of penetration can be of marked degree.

Ed
TGMM Family of the Bow

Rick, In fairness to Zwickey, the No Mercy is NOT just a narrowed Delta. Comparing the heads will reveal that No Mercy blades are created by cutting a different blank. I don't doubt that some prototypes were made by narrowing Deltas. I like Zwickey products and wouldn't shed any tears if they were the only commercially available broadheads.....but I have to say that the No Mercy appers to me to offer nothing over the similarly profiled STOS except green paint and a different(rougher)weld pattern.

Can anyone tell me how wide and how many grains is this new (no mercy) broadhead is,I have not seen it yet. THANKS.

Delta
Look at the 3rivers web site they have them listed there.

I think my deviation problem may be a harder to define Dr. Ashby. Shooting selbows of around 45# with arrow weights between 550-650gr I believe arrow speed is a consideration here also. Like that fast spinning top contacting an object and spinng away a slower spinnig top will cause a wobble when it hits an object. Were a fast arrow will just punch on through a light skinned animal and hold it's line of flight I believe my slower arrows can't handle the torque of the single bevel and same side fletch as efficiently as the faster arrow and arrow path deviates somewhat. Thus the barrel rolls or leaners I was expericening in my mine belt target. That double bevel tanto tip solved my problem vs the same side single bevel tanto tip causing a better bite or simply providing better steerage, or both. Probably way off with my thoughts here so I will do further testing later on.-ART

Delta, they're 130 grains and are available in double bevel, or single bevel left and right.  They also have a slightly convex blade angle (like an Eskimo but less so).

http://www.braveheartarchery.us/new_page_16.htm

I'm not a real technical guy, and after reading the responses here I'm still unsure of what to do with the tips on my No Mercy's.

I'm thinking try working the tips several different ways and sticking with what comes out sharpest at this point !

Brad, I'll try to get you a pic of what I do and post it tonight.

Well, unfortunately the macro on my camera rather sucks at capturing broadhead tip detail. Sorry.

Don't know anything about the No Mercy's Bard but here's how I re-made my tips (double beveled) per Dr Ashby's instruction.-ART B