VPA broadhead flight issue

[Pac8541]

I'd like some feedback from you guys concerning a few odd flight issues I'm experiencing with these heads. Here are my specs:

 

Bowtech Allegiance 70lbs, 27.5" DL, 80% let off.

ACC Pro Hunter 340's, 26.5", 3 fletched with 3.6" Flex Fletch right helical.

VPA 2 blade 175gr and 3 blade 150gr.

 

OT2 software numbers

175gr heads: 501gr total arrow weight, 245fps, 15.29% foc, 339 dynamic spine.

150gr heads: 476gr total arrow weight, 252fps, 13.57% foc, 351 dynamic spine.

 

Bear in mind that my bow is untuned for these heads and I've been shooting both new heads and vanes for groups to see which combination shoots best. I've settled on the longer vanes as they seem to stabilize the arrow faster. Both heads are flying pretty well. Both are shooting lower than my former arrows but are significantly heavier. I initially experienced some left deviation but seem to have solved that after diagnosing my shooting form. The issue is the lighter heads are dropping about twice as much as the heavier ones and this increases with range.

 

Photo 1 below shows the 175 POI from 20 yds. POA was the "O" in "BLOCK." Photo 2 is the 150 from the same yard line. Photo 3 is the 150 head from 30yds using my 30yd sight pin after it struck a rock at the base of the target and went under the target. The 175's shot from 30yds with the correct sight pin hit in the same place as they did from 20yds.

 

Is this wind planing? The only variable here is the head. Thoughts? Experience?

 

[WHT_MTNMAN]

I shot them for a while and they are one of my favorite heads. I never got the solid head to shoot well...I started shooting the vented vpa's with better luck. Very picky to your form and I believe not good with high speed bows. That's my experience.

[HuntHarder]

2 blade vs 3 blade. I would think your bow might be sitting a little nock high and the 3 blade has more surface area to plane lower

[JACK]

Been playing around with some of the same stuff you are...the head isn't the only variable...FOC and spine are different too...both can make a difference...

[Pac8541]

Been playing around with some of the same stuff you are...the head isn't the only variable...FOC and spine are different too...both can make a difference...

Well, its the only variable I have direct control over, is what I meant. I get that spine and FOC will change and that will happen with every different weight head I put on there.

 

I'm confident I could tune either head to shoot well I'm just a little baffled as to why its happening. I wouldn't say my bow is anything close to a speed demon but planing is about the only thing I can think of. Nock/rest tuning would likely cure the low hits, its not like they're all over the place or inconsistent. But with what I'm seeing initially, I may just go with the 2 blade heads anyway: the heavier arrow is shooting great.

[JACK]

Uhhkay...you're building the arrow you are in control of all the variables...Happy Hunting!

[hunt crazy in ca]

played with those heads for a while, love them(VPA)...but they plan out to much, switch to the vented(VPA) 3-blade and you will be fine.

A good tune on your bow will only help ALOT!

good luck

[Pac8541]

Yes Jack, I do have control of all the variables when building my own arrows. The point I'm at though is I've chosen and purchased the shafts in the most versatile spine for me, I've chosen the nocks I want based on what I'm trying to achieve in terms of visibility and reliability. Neither of those 2 items am I willing to replace at this point due to both cost and faith in the product; I see no reason to question them. I've asked for samples of 2 different vanes and shot them both side by side to determine which length/profile stabilizes the arrow fastest and flies the quietest. Now with those parts of the equation solved, so to speak, I move on to broadheads and have chosen 2 that I feel are good candidates for what I'm trying to achieve. I have no previous experience with VPA heads nor do I have experience with heads this heavy. I decided to shoot them without touching the bow because by leaving the bow untuned for these particular heads I felt that would give me a reliable baseline from which to start. It shot my previous arrows and heads just fine but those were up to 75gr lighter than these and thats just in the head. So I guess what I'm trying to achieve right now is to determine whether or not either head rises to the top in terms of inherent accuracy or flight. Its something I do with precision rifles: establish a baseline of sorts and attack one "variable" at a time. I don't need or expect bullets to match my POA immediately but I shoot them to see how they group. If they do well and my rifle likes them, then I start making refinements to my equipment to achieve POA/POI. I don't see why this wouldn't work with a bow.

 

Not trying to be a dick or argue but I want to be clear as to what I'm doing. Tuning the bow is one thing, I think I may be able to tune these elevation issues out of the flight. But if there's something I'm missing regarding this particular broadhead or the experiences others have with their flight then I'd rather know about it now before I spend anymore time with them. I appreciate all the feedback, thanks.

[JACK]

I completely understand...Im not trying to argue either...How does each broadhead shoot on an unfletched shaft? How does each broadhead group in comparison to the same grain field point?

[Pac8541]

Good questions, haven't tried either. I've run out of time over my weekend and head back to work tomorrow so it'll have to wait until Sunday, earliest. I'll be ordering same weight field points from 3 Rivers Archery (thanks again, elpepe!) this week. For the moment I've lifted my rest a bit and brought it a hair right to bring things into the middle. Thats the only adjustment I'm going to make before I finish the rest of the shafts.

 

And replace my "stabilizer" with a stabilizer.

 

And restring the bow cuz I'm still running the OEM string.

 

And maybe find a lighter weight way to guard the cables other than the Windstalker I'm using now.

 

Good grief, what the heck am I doing....??