Arrow spine help

[RockyMountainWest]

Hello all. I’m planning on building some new arrows. Looking at black eagle x impact shafts along with their FOCOS insert/outsert system. I plan on building an arrow around 500 grains. I will most likely be using a 125gr fixed blade broad head with an 80gr or 100gr outsert/insert. I want to have about 200 grains up front. I’m shooting a Mathews traverse. The limb bolts are maxed out so I’m at about a 69lb draw. My arrows are 29.5 inches front the throat of the knock to the end of the insert. That’s the length I’ve always ran and it works best with my draw length. With that being said, the black Eagle FOCOS insert/outsert system adds about an inch of outsert onto the end of your arrow so I may consider cutting my arrows down to accommodate for that which will make my arrow from the throat of the knock to the end of the carbon shaft at about 28.5 inches. I’m not sure if I should stick with a 300 spine or if I should go with a 250 instead. Any input appreciated. These arrows are expensive so I want to make sure I get the right ones. I tried emailing black Eagle but haven’t heard back. Thank you very much.

 

[Insomnia]

What's your actual draw length?

 

[Mighty Mouse]

qSpine/OT2Go says 284 is your "optimal" spine at the specs listed below. 250 or 300 should both work just fine.

Bow: 338 fps IBO, 69# DW, 29" DL, 33" ATA, 6.625" BH, 80% LO
Arrow: 29" C2C, 125 gr head, 80 gr insert, 9 gr nock, 3 vanes at 7 gr each

 

[RockyMountainWest]

What's your actual draw length?

qSpine/OT2Go says 284 is your "optimal" spine at the specs listed below. 250 or 300 should both work just fine.
View attachment 510454
Bow: 338 fps IBO, 69# DW, 29" DL, 33" ATA, 6.625" BH, 80% LO
Arrow: 29" C2C, 125 gr head, 80 gr insert, 9 gr nock, 3 vanes at 7 gr each

Awesome. Thank you. What app or website is that?

 

[RockyMountainWest]

What's your actual draw length?

I’m shooting a 29.5” draw mod so my total draw with d loop and all is about 30”

 

[Billy Goat]

I'd go 250. Can't get too stiff with a broadhead on the front in my experience.

 

[Mighty Mouse]

Awesome. Thank you. What app or website is that?

It's an app called OT2Go->Spine. The app is glitchy and tries to nickel-and-dime you with upgrades, but for a few bucks it's fun to play around with.

 

[Insomnia]

You could probably leave your arrows at 29.5" c2c with the 250s and if they're acting a little weak, you have some room to cut them down with the focos system.

 

[JDZ]

You’ll be a touch under 500 gr with .300 spine shafts. A bit over with .250 spine.

My X-impact 300 with 125 gr tip and 80 gr FOCOS are just under 30 inches from throat of nock to front of FOCOS and weigh 490 gr.

Are you sure you can cut the shafts that short and not have the back of the FOCOS hit the rest? The FOCOS adds to the front of the carbon by 1.1 inches, but it also goes back over the end of the carbon by .7 or .8 inches. That necessitates your arrow to be nearly 2 inches longer than a regular shaft with insert and point.

 

[entropy]

I've not played around with X-Impacts at all, but I've built several sets of Carnivores, Rampages and Spartans for both myself and family members. All the arrows I built for myself have been 250 spine with Ethics outsert systems; never less than 100 gr total weight for the outsert system, always using either 125 or 150 heads, so 225-270 total weight up front. All of these tuned well for my bow (VXR 31.5, 75 lb 80% 30.5" mods).

One set I built for my father in law was on 300 spine Rampages though. He's north of 70 and doesn't want to pull more than 50 lbs nowadays, but he's also 30.5" for draw. I hemmed and hawed between getting him 300s or 350s, because he wanted the 120 gr Ethics outsert and planned on using 125 gr heads; finally decided that safe was better than sorry and went with the 300s. After I built the bareshafts, I decided to play around wtih them a bit on the VXR. I was pretty surprised that I was able to get them to a bullet hole at 15 feet with no problem; I figured for certain my bow would turn them into pretzels.

The experience didn't inspire me to start building 300 spine arrows for myself, and it's not exactly the same setup you're looking at, but off the cuff I personally wouldn't be too scared of trying the 300 spine with your setup. If you have time and money to tinker, you could just buy 3 of each from Lancaster and try them both. Careful though, you'll wind up like me with oddball arrows all over the place and a wife asking wtf...

 

[S.Clancy]

You will prob be good with 300 spine. If I were you, I would cut them long, set your bow to factory specs and then shoot bareshafts through paper until you get close to a bullet hole, cutting the arrow down as needed. That will give you your best fit arrow for your bow.

 

[RockyMountainWest]

You will prob be good with 300 spine. If I were you, I would cut them long, set your bow to factory specs and then shoot bareshafts through paper until you get close to a bullet hole, cutting the arrow down as needed. That will give you your best fit arrow for your bow.

How exactly does that process work? Do I buy shafts and don’t cut them down and then shoot through paper, if the arrow is tearing left I’d cut the arrow down? And just continue to do that until I get a bullet hole? Obviously not cutting it down too short with my draw length. Thanks

 

[Billy Goat]

How exactly does that process work? Do I buy shafts and don’t cut them down and then shoot through paper, if the arrow is tearing left I’d cut the arrow down? And just continue to do that until I get a bullet hole? Obviously not cutting it down too short with my draw length. Thanks

In a centershot compound bow, a weak shaft usually represents itself with inconsistent results. With broadheads on different arrows, or bareshafts you won't get well defined patterns when comparing them to fletched.


The left/right impact stuff is mainly reserved for traditional stuff where you are depending on archers paradox to wrap the arrow around the riser.


Paper gives a small snapshot at a point, if you are going to use it, shoot it at multiple distances.

 

[S.Clancy]

How exactly does that process work? Do I buy shafts and don’t cut them down and then shoot through paper, if the arrow is tearing left I’d cut the arrow down? And just continue to do that until I get a bullet hole? Obviously not cutting it down too short with my draw length. Thanks

I'll go through I how tune my arrow to my bow if I go with new arrows (if you don't change your setup, you obviously don't have to do this).

1. Set your bow to poundage/draw length you will shoot and set the rest to the factory centershot (you'll have to look up the bow specs for this, most are around 3/4" from the riser)
2. I use a spine calculator to make sure my spine is at least close. There are several apps you can use, I use the Victory Arrows spine calculator (https://www.victoryarchery.com/arrow-guide/)
3. I cut my arrows long (by the spine calculator, weak). So, for my 28" draw length I would cut them ~29"
4. Put insert and point you are going to use in 1 arrow, cut it to the length above. I will cut off both sides of an arrow.
5. Insert nock and shoot through paper. Shoot a couple times to make sure it is consistent. You are looking for whether it is a weak or stiff tear. Because you cut the arrows really long, it should be weak. Weak should show left (nock left) tear. If it is stiff, you screwed up, you need to start over with a longer arrow.
6. Take the nock off, cut 1/4" off the back of the arrow. Square and put nock pack on.
7. Shoot arrow through paper a couple times to get a consistent tear.
8. If tear is still weak (the tear should decrease in amplitude tho), complete steps 5&6 until you get ~ a bullet hole (you are shooting bare shafts, so you should get close, maybe not exact bullet hole as this depends on form alot). If you get a bullet hole, congratulations, you are done. You can now cut the rest of your arrows to that length.

After this I will fletch the arrows, leaving the original bareshaft. I then go out and bareshaft tune at the range out to 30-40 yards. If you do the above steps, your bow is really well tuned and will shoot any broadhead excellently.

***If you are seeing inconsistent results in the paper tune part, you need to work on your form and hand pressure. No amount of good tuning is going to make up for shit form***

 

[Mighty Mouse]

Insert nock and shoot through paper. Shoot a couple times to make sure it is consistent. You are looking for whether it is a weak or stiff tear. Because you cut the arrows really long, it should be weak. Weak should show left (nock left) tear. If it is stiff, you screwed up, you need to start over with a longer arrow.

Is the "nock left tear = weak spine" rule true for both right-handed and left-handed shooters?

 

[S.Clancy]

Is the "nock left tear = weak spine" rule true for both right-handed and left-handed shooters?

I don't know, I don't believe in "left-handed".....

 

[RockyMountainWest]

I'll go through I how tune my arrow to my bow if I go with new arrows (if you don't change your setup, you obviously don't have to do this).

1. Set your bow to poundage/draw length you will shoot and set the rest to the factory centershot (you'll have to look up the bow specs for this, most are around 3/4" from the riser)
2. I use a spine calculator to make sure my spine is at least close. There are several apps you can use, I use the Victory Arrows spine calculator (https://www.victoryarchery.com/arrow-guide/)
3. I cut my arrows long (by the spine calculator, weak). So, for my 28" draw length I would cut them ~29"
4. Put insert and point you are going to use in 1 arrow, cut it to the length above. I will cut off both sides of an arrow.
5. Insert nock and shoot through paper. Shoot a couple times to make sure it is consistent. You are looking for whether it is a weak or stiff tear. Because you cut the arrows really long, it should be weak. Weak should show left (nock left) tear. If it is stiff, you screwed up, you need to start over with a longer arrow.
6. Take the nock off, cut 1/4" off the back of the arrow. Square and put nock pack on.
7. Shoot arrow through paper a couple times to get a consistent tear.
8. If tear is still weak (the tear should decrease in amplitude tho), complete steps 5&6 until you get ~ a bullet hole (you are shooting bare shafts, so you should get close, maybe not exact bullet hole as this depends on form alot). If you get a bullet hole, congratulations, you are done. You can now cut the rest of your arrows to that length.

After this I will fletch the arrows, leaving the original bareshaft. I then go out and bareshaft tune at the range out to 30-40 yards. If you do the above steps, your bow is really well tuned and will shoot any broadhead excellently.

***If you are seeing inconsistent results in the paper tune part, you need to work on your form and hand pressure. No amount of good tuning is going to make up for shit form***

Thank you very much for that. Sounds like the way to go when building new arrows. The only thing that’s going to be a pain for me is that I don’t own an arrow saw and they’re kind of expensive for a decent one. Also, what glue do you use in order to remove the inserts multiple times and doesn’t the glue need to cure for a bit of time? I dont know if my local archery shop would be ok with me using their paper target and cutting down arrows for me. They always are super busy too. Any input appreciated.

 

[S.Clancy]

Thank you very much for that. Sounds like the way to go when building new arrows. The only thing that’s going to be a pain for me is that I don’t own an arrow saw and they’re kind of expensive for a decent one. Also, what glue do you use in order to remove the inserts multiple times and doesn’t the glue need to cure for a bit of time? I dont know if my local archery shop would be ok with me using their paper target and cutting down arrows for me. They always are super busy too. Any input appreciated.

I have my own saw, if you keep your eye out you can get them pretty cheap, I got mine for 30$.

I cut off the back end of the arrow. Just make sure you are squaring it.

 

[RockyMountainWest]

I have my own saw, if you keep your eye out you can get them pretty cheap, I got mine for 30$.

I cut off the back end of the arrow. Just make sure you are squaring it.

Where did you find a used arrow saw? And what kind of glue are you using to be able to quickly and easily remove and replace inserts during the cut down process?

 

[Mighty Mouse]

I don't know, I don't believe in "left-handed".....

Reason I asked is because I often hear guys say "nock left = weak/nock right = stiff for a righty, vice versa for a lefty." This makes sense for traditional bows shot with fingers where the arrow typically starts away from centershot, but I don't think it has much relevance to a compound bow not influenced by fingers on the string with a cut-out riser that allows the arrow to remain in line with the string path throughout the shot. I can't conceive of why an overly weak arrow would leave a compound bow nock left and an overly stiff arrow would leave nock right. If you have a theory on that, I'd be interested to hear it.

I've played around with intentionally shooting significantly over and under-spined arrows (relative to what charts/calculators recommend) out of various compound bows and haven't witnessed the purported weak-left/stiff-right tear patterns. Arrow spine certainly can affect how a compound bow tunes (FWIW I believe the range of appropriate/acceptable spines is significantly wider than most people think), but I don't think the left tear = weak/right tear = stiff advice necessarily holds true.

If your method works for you, go with it, but when I see a horizontal tear, I don't immediately start adjusting arrow spine. I adjust cam lean/lateral position first then rest windage if necessary. Some combination of those two adjustments has always corrected my left/right tears.