Thinking I’m underspined....chime in.

[RemiR7]

With everything going on and typically this time of the year I tend to fart around with my setups. I’m wondering if I’m underspined. I’m running axis 340s at 26” c2c, 75 gr brass inserts, 6” wrap 9gr, xnock 9gr, 4 fletch 24gr, and this past year I ran a 125gr Montec,TAW 501 gr. Now I’m shooting a bowtech realm SR6 at 27” draw at 74lbs. Now I realize looking at that you may say I’m underspined and that what I thought, and I ran the numbers last spring when I had pinwheel and it sure enough showed weak and surprisingly I was still able to get it to tune fine after some time and help with my pro shop. I had a gentleman from here run it again and I noticed it showed weak again but also showed I should be shooting low-mid 280fps with that setup and after having it chrono’d i was shooting 259-260fps and after talking to both the techs at the shop they mentioned that bow wasn’t as efficient with a heavier setup arrow and shorter draw which I would say is right judging from what pinwheel said and the actual numbers were. Now maybe pinwheel isn’t as accurate? Not sure. Now could that mean since that bow is not generating the stats they propose it will mean my arrow isn’t possibly underspined out my that bow. Reason I’m asking is because I’m about to make the dip into some ironwill components/broadhead a and don’t care to buy several dozen more arrows to move up a spine when I was able to get the ones now to tune just fine....maybe I’m wrong. Someone with some knowledge or similar setup chime in please. Once again pinwheels numbers don’t reflect what my actual numbers are.

 

[Rob5589]

I think you answered your own question; you have the bow tuned fine. I recall reading that the SR6 loses quite a bit of speed at shorter draw lengths.

 

[RemiR7]

I think you answered your own question; you have the bow tuned fine. I recall reading that the SR6 loses quite a bit of speed at shorter draw lengths.

that’s what thought being I was able to get it to tune and the fact that the bow with my specs just isn’t as efficient as what they advertise. When I did have pinwheel and was messing with it I believe the numbers I was pushing out reflected that bow being IBO around 335ish and not the 352 as they show.

 

[Beendare]

You can get an underpinned bow to tune with FP's....where you run into problems sometimes is when shooting BH's.
...and hunting conditions with potential minor form problems causing accuracy issues.


I would bump up to 300's

______

 

[Zac]

You could probably run a hundred grain head and be fine.

 

[NYyotekiller]

I would buy just a couple 300 Axis and try them and see how they tune for you Before buying a dozen of them. I bet you that they’ll shoot much better than the 340’s.

IME the 340 Axis are underspined when shooting the larger fixed broadheads like you’re shooting and more so when shooting higher poundage over 70#.

Like @Beendare said, best bet is to switch over to the 300’s.

 

[Billy Goat]

What quantified your bow as being in tune?

If you have broadheads hitting with your field points out to the yardages you intend to shoot that's what I would use, along with good arrow flight. No fishtailing, or porpoising.

Software is to get you in the ballpark. You should be confirming tune, and for me thats a lot more than holes in paper.

 

[RemiR7]

What quantified your bow as being in tune?

If you have broadheads hitting with your field points out to the yardages you intend to shoot that's what I would use, along with good arrow flight. No fishtailing, or porpoising.

Software is to get you in the ballpark. You should be confirming tune, and for me thats a lot more than holes in paper.

Exactly just that. I was able to get the broadhead to hit fairly decent and consistent with my field points out to 50 which anything past that I really just do anymore with fixed heads. Although before I got to the broadhead portion/field point when I first got the bow and bare shaft tuning was a bit of a fiasco to be honest, which is what led me to think these were too weak of an arrow to begin with, but after a lot of time and cutting down on the arrow and adding a wrap helped a bit. I will say I’am going away from the 125gr heads and back to 100gr.

 

[Billy Goat]

Exactly just that. I was able to get the broadhead to hit fairly decent and consistent with my field points out to 50 which anything past that I really just do anymore with fixed heads. Although before I got to the broadhead portion/field point when I first got the bow and bare shaft tuning was a bit of a fiasco to be honest, which is what led me to think these were too weak of an arrow to begin with, but after a lot of time and cutting down on the arrow and adding a wrap helped a bit. I will say I’am going away from the 125gr heads and back to 100gr.

Sounds like your on the edge. I haven't seen a down side to being stiff with broadheads. Going to be up to you. If it tunes it tunes.

 

[RemiR7]

To those that chimed in on this thread. I spent the better part of yesterday playing around with different weighted heads at various ranges and taking note of the groupings between the two over several hours of shooting. As some mentioned that I need to bump up a spine or that I was on the edge I believe were correct after yesterday without a doubt. While I was able to get the arrows to tune at my previous setup mentioned in the original post after some headache and finagling. Dropping down to a lower weighted head (100gr) I noticed after a hundred or so arrows shot at each head the lower weighted head seemed to group better overall. I'm guessing the lower weighted head resulted in the spine not being as weak a 125gr head and better arrow flight and in result bringing my groups tighter. With all that being said and obviously being on the bubble or underspined as some of you mentioned.I ditched the 340s and went to 300s axis match grade at 26" c2c, 50gr brass insert, 7" wrap, 4 fletch, xnock, with a 25gr IW collar, and IW S100 heads. tanks for the feedback and it only back up what i thought, but was stubborn and trying to find ways around buy a whole new setup.

 

[bignocks]

just curious if you tried lowering your poundage. Seems like that might be a easy way to know for sure. Also as for the speeds did you double check the mods are set on performance and not comfort. Good luck

 

[insanelupus]

For future use, fast and free and it seems to be reasonably accurate.

Arrow Guide - Victory Archery

www.victoryarchery.com

 

[Block]

I shoot a 300 VAP with 55g titanium insert and 125g rage (485 grain total) much better groups with My 70# bow than my #80 Ultra.,, I “think” due to it being right on the edge of being under spined. Probably even guna drop back down to 100 grain head to help the spine a little more.

 

[RemiR7]

just curious if you tried lowering your poundage. Seems like that might be a easy way to know for sure. Also as for the speeds did you double check the mods are set on performance and not comfort. Good luck

Yes mods are on performance setting and have been and while I probably could back off the poundage and would probably work. I don’t care to lose anymore speed as I’m already at the 259-260 mark and was lower than what I initially wanted and thought I would get out of it. I’ve gotten used to it over the past year and is no issue for me. New shafts and components are on their way and looking forward to building some new arrows.

 

[RemiR7]

For future use, fast and free and it seems to be reasonably accurate.

Arrow Guide - Victory Archery

www.victoryarchery.com

I did use it and not sure how accurate it is, but it did show I was just underspined by very little.