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Factual advice on choosing arrow spine
Would like some fact based information concerning determining if poor broad head flight can be caused by your arrows being over spined or not. I was shooting the sadly recently discontinued made by Beaman for Cabelas Stalker Extreme carbon arrows I fletched myself for. They are 340 arrows cut at 29.5". After I tuned the bow and got it shooting FP's extremely well moved over to BH's. I was very unpleasantly surprised that my BH's were impacting 8-10" to the right away from my FP's consistently, but almost never up or down. I started to play with the rest but wasn't able to get them any closer together than 4". I asked the input of a very knowledgeable pro shop owner and he said in his opinion my arrows were 1/2" to long and over spined. So I tried out a 400 spined arrow 1/2" shorter and instantly my distance from POI from FP's to BH's shrunk from 4-4.5" to 2"-2.25". Played with my rest and ended up getting my BH's consistently under an inch from my FP's and only change I made was weaker spined slightly shorter arrows. If it would prove helpful my Darton DS3714 is set at 56-57lbs DW, DL of 29.5" and I use a mechanical caliper release. The BH's I am using are 100 grain Wasp Boss SST 3 blade 1-1'16" CD. I'm asking because I have been told more than one person I was not over spined at all and with todays carbon arrows arrow spine is not all that important and shouldn't have caused my poor BH flight. I have also been told and have read it at other forums people saying you can almost not be over spined or and in my case 340 spined arrows should have had BH flight equal to the 340's I replaced them with and I basically wasted my money buying new arrows as I have about 20 of the 340 Cabelas Stalker Extreme arrows left. So does anyone know based on my set up was a 340 spined arrow over spined and the cause of my BH flight issues or not?
If one is border line between 2 spines, I prefer the stiffer of the two, esp shooting fixed heads ..
Now, that being said, the 340's are stiff for your set up .... Im shooting Velocity XT 340s at 62 lbs, 28" arrow, 100gr Slicktricks draw is 30" out the main bow. I shoot 75/95s(340 hunter XTs) 28" at 67lbs /29.5" draw with Steelheads out of the back up bow ....
Yes, you can be over spined
Poor broadhead flight from being overspined?
Less than optimal broadhead flight due to being overspined?
Being that far off with BH's is signs of another problem, tune, fletching contact, bad limb, timing etc. Let alone wirh being over spined
Shooting 56 pounds of draw weight and a 340 is likely going to be a problem if everything else tuning wise is not perfect. When people say stuff like its impossible to be over spined, they mean within reason. You are definitely on the outer limits of reasoning shooting that arrow spine. Plus, you've likely got something else not quite right too.
I agree that you have something else going on. I would check cam lean or cam timing. I shoot 57# with 29.5 draw and shoot victory 350 arrows with 100 grain muzzy and it shoots great. Being too stiff is just showing another problem. If you shot with fingers then you have a different animal.
Also watch John Dudley on nock on on YouTube. This would be a good place to start. Greg
"I asked the input of a very knowledgeable pro shop owner and he said in his opinion my arrows were 1/2" to long and over spined."
One or the other can be true insofar as the spine question is concerned, but not both.
I should add, toss heavier (125-150 gr.) BH's and FP's on that arrow and see if it cleans things up. I am betting not.
Bow tuning, arrow tuning, improper form and combinations of above can all cause what you're describing! I'd start with making sure bow is in specs and check for cam lean, have somebody observe your cams from directly behind at full draw, also have somebody that is an accomplished shooter, shoot your bow if you can if all else checks good, torquing your bow will really screw up your broadhead flight!
LOL!! I always get beat up when I talk arrow spine because I think ost guys are over spined. I shoot a .400 spine cut to 27"s with 175 grain points. I shoot 67#s and draw 27.5"s and get perfect flight with both field points and broadheads hitting exactly the same spot out as far as I care to shoot. Folks have to remember that a .340 spine is listed that it will shoot out of lets say 80# bow so to protect themselves arrow manufacturers have to make sure it will be safe even at full length be shot out of an 80# bow with a standard 100-125 grain head. So think how stiff it has to be if that is the case when it is 32 or 33"s long. I know they spine at 28"s and use a 14" center but again they have to make sure the average joe blow don't blow up an arrow and cause injury. Once you start cutting an arrow down it begins to stiffen and a lot more than most folks think. That is why when one takes an arrow that can be shot from an 80# bow full length and start cutting it down they wonder why it gets to stiff for their set up. Again though, I will get beat up over this absurd notion! Shawn
As long as i can get bare shafts shooting with fletched at 25 yards i dont mind them showing a bit of a nock right stiff reaction. I think the consistent small inparted direction in my tune gives me consistancy. Its not often i agree with shawn, however I do feel that the trend to using overly stiff arrows is boarder line fadish at this point. For example just for shits and giggles i tuned a bow recently with three diffent spine arrows, 390, 350 and 300 acc' all with 75 grain brass inserts and 100 grain heads and all 27 inches..... you could have taken you pick with what shot best.
I've shot a tad overspined for decades with a compound and drop away rest....my bow with BH's is more accurate than I can shoot it.
"One or the other can be true insofar as the spine question is concerned, but not both." Absolutely correct and great pick up, shortening the shaft stiffens spine. If that is what the shop actually said I'd find another shop..........
Like folks above wrote..... this isn't a spine issue IMO. But easy enough to prove, either try a heavier head as Matt said or if possible take a few turns in on your limbs and see if it clears up.
As x-man has stated here several times, I too have taken several broken or otherwise "donated" 340-300 spine arrows and cut them down to 24-26" for kids shooting 40-50 lb bows.... they shoot great, so well the kids take a fair amount of pride and glee in a game of busting your and others arrows in the target.... giggling and laughing the whole time. Young eyes and young fearless nerves. I've noticed getting poorer eyes and twitchy nerves lately..... Hey! You kids! GET OFF MY LAWN!.....
IMO with a hunting rig out of a timed and tuned compound bow, release, fall away, etc.... you can't really be overspined. I've never seen it. Issues having a decently stiff spine we've always been able to trace to something else. (where have I heard that before...???) That's something that is a carry over from tuning trad bows. Compounds are adjusted by rest (or yoke) and timed, shot with release to get as perfectly straight launch as possible out of them.
Only way overspined may make a difference in a compound is if the bow is not timed exactly and is out of sync somehow, using the shaft flex to try and correct for the poor launch. See: trad bow tuning. Finger release and riser/fletching contact to deal with.
Otherwise, decent form out of a timed and tuned compound bow, shaft flex is something you are trying to eliminate, not induce.... however once "eliminated" (or stiff enough to have little effect).... for all practical purposes you will gain little to nothing by going stiffer. But you won't be hurting much either, but for speed from a normally heavier shaft.
Underspined however...... that a whole 'nuther issue and can seriously mess up tune, ESPECIALLY with FBBHs.
What arrow rest are you using? The type can make a difference; is it a drop away, biscuit, prong or older style with a Berger button?
I found that 400 spine flew better out of my 60 pound bowtech experience than my 340s, they where more forgiving, I loved my darton bows but always had issues tuning, I could get it close but never perfect, same as any non static yoke bow I have owned
The shop owner suggesting the arrow was to stiff is correct but saying they are a half inch to long and should be cut is ignorant. If you cut a shaft it gets stiffer, not weaker.
For what its worth, I ran your setup thru OT2 which I have found is usually a pretty close starting point. 340 is to stiff unless you want to run a 175gr head. If you went to a 350 spined arrow, same length, with a 125gr head, it should fly well. Ends up dead center spine wise which is where you want to be.
DMTJAGER. You have got a lot of good info on here. Hope it helps. I personally believe with a truly tuned bow both of your arrows would work. Shawn, I don’t disagree with you at all! Shot 400s for years and now 350s for weight. Both shoot great. May try some 500s sometime to see for my self. I do enjoy playing with this stuff.
Broadheads right would mean underspine, if it was a spine issue. Broadheads right should equate to a left tear on paper.
I fought a very similar issue on my Hoyt pro difiant turbo last year. I ended up swapping shims (right shim 1/8” left shim 1/16”) on my bottom cam which moved my cam to the right. My issue went a way after the shim move.
Definitely not overspined. There are other problems that need to be addressed.
First thing to do is find a new shop to attend for advise.