Choosing spine for rip tko

[martie88]

Going to build some new rip tok arrows for this year's elk hunt shooting a hoyt ventum pro 33 at 31" draw have my current arrows cut at 30.5 . Will have 20 grain lighted nocks, 3 6.1gr vanes, 50grain insert, 10 grain collar , 125 gr broadhead will put be somewhere around 15% foc but trying to decide if I should go 300 or 250 spine any suggestions?

 

[Mighty Mouse]

qSpine/OT2Go puts you closer to 250 assuming 70# draw weight.

 

[martie88]

qSpine/OT2Go puts you closer to 250 assuming 70# draw weight.
View attachment 692619

Thank you!! yes shooting 70lbs. I have been trying to figure out how to get that software but I can't get on the site for some reason

 

[Mighty Mouse]

Thank you!! yes shooting 70lbs. I have been trying to figure out how to get that software but I can't get on the site for some reason

Pinwheel has been having some issues lately. I think the mobile app versions are no longer available for download and maybe the desktop version too. Archer's Advantage is another popular spine calculation software.

 

[jbelz]

Also, at a 31" draw they do not need to be cut at 30.5" – I'm at 31" draw and I cut mine to 29 1/4 (you might feel safer at 29 1/2). That will stiffen the arrow up a bit as well, and it could put you closer to 300 territory.

 

[doc holiday13]

90% chance you'll need to be a 250. but you could order 3-300 spines and see how well they fly

 

[martie88]

Looks like 30" at 250 will be the best used archers advantage. It's

 

[5MilesBack]

Holy cow! What's the IBO on that bow? 310 with an almost 500gr arrow at 31" draw......

My Traverse is 335 IBO and at 32.5"+ draw I can't get close to 310fps with 500gr RIP TKO 250's at 70lbs with 30" arrows.

 

[Mighty Mouse]

Holy cow! What's the IBO on that bow? 310 with an almost 500gr arrow at 31" draw......

My Traverse is 335 IBO and at 32.5"+ draw I can't get close to 310fps with 500gr RIP TKO 250's at 70lbs with 30" arrows.

qSpine predicts 290 fps at 70#, 31", 500 gr, 334 fps IBO...that seems about right. The speeds shown in the AA screenshots above don't look realistic to me.

 

[martie88]

Yea im not sure why it's giving those speeds. Definitely not realistic. Not sure if I have something set wrong or it's just the program...

 

[Bump79]

250 spine

 

[Archerichards]

I have a 31" DL too. Archers Advantage says I should shoot a 250, so I do, even though it is "marginal stiff" per AA. I am getting good results though, especially shooting fixed blade broad heads which tend to behave better with a somewhat overspend arrow.

I have decided I would give up some FOC and speed in order to get a better performing shaft for my fixed blades. Mind you though, I am still getting ~285 fps, so, plenty good speed.

 

[Eastonsgrandpa]

Definitely a 250. Good thing is there is only a .1 grain difference between 300 and 250.