Help with Arrow Spine

[P-Lar]

I am looking at different arrow spine charts for whitetail hunting and general target shooting and I'm thinking I may be underspined due to the extra weight I have up front. Currently running a 350 spine arrow but I'm thinking of going to a 300 spine and wanted to get ya'lls opinion.

Bow specs:
Mission MXR, 27" draw length, 70 lbs draw weight

Current arrow:
Black Eagle Zombie Slayers
350 Spine
26.5" carbon to carbon
8.0 GPI
18gr total vanes
8gr nock
125gr field point
14gr insert
150gr of extra weight (gold tip fact weights 50gr x3) screwed into the back of the insert
Total weight of around 527gr

Proposed arrow:
Black Eagle Zombie Slayers
300 Spine
26.5" carbon to carbon
9.2 GPI
18gr total vanes
8gr nock
125gr field point
14gr insert
150gr of extra weight (gold tip fact weights 50gr x3) screwed into the back of the insert
Total weight of around 558gr

What do ya'll think - should I be running a 300 spine arrow instead of a 350? Another option I was thinking about was removing one of the 50gr gold tip fact weights (so 125gr tip, 14gr insert, & 100gr weights up front) in the 300 spine arrow to bring the total weight to around 508gr since that arrow has a higher GPI than the 350 spine arrow. This is my first bow and have only been shooting a little under 2 years so appreciate any help from the more experienced archers/hunters. Thanks!

 

[Lowg08]

I’d personally go 250/260 but 300 may be enough.

 

[Rob5589]

Why are you wanting to change?

 

[OR Archer]

My question is why do you think you need almost 300gr on the front of your arrow? Did you drink the Ranch Fairy kool aid? That bow and arrow set up is probably lobbing rainbows.
50-75gr total insert weight is plenty when combined with a 100-125gr head. And for deer size game an arrow around 450gr is way more than enough. Hell it’s plenty for elk as well. Just some points to consider in your tinkering. I just wouldn’t go down the extreme FOC heavy arrow route with your setup.

 

[Mighty Mouse]

A spine calculator is going to recommend 300 with that much front end weight. But 350's may still fly fine out of your bow. Have you tried any paper/bareshaft/broadhead tuning?


You're on the heavy/slow end of the spectrum for a compound bow with either of those arrows, which may serve you just fine if you're taking shorter shots at known distances. But you definitely have room to go lighter/faster, which would tighten your pin gaps and be more forgiving of range estimation errors. Before ditching your 350's, maybe try removing some of the FACT weights to see how much your trajectory changes. You may like it better with less weight (and it would put you closer to "optimal" spine).

 

[Billy Goat]

If you are aiming for that much arrow weight, lean more on a heavier shaft to get there.

It's all about balance. You aren't gaining anything with 30% foc, if you want foc , go for 15, and have an arrow behind it that is suited to the weight range you want to be.


I think as you get more rounded in your experience, you will drop your TAW some. But if it's where you feel like you want to be, carry on.

 

[P-Lar]

Why are you wanting to change?

Not necessarily "wanting" to change, I was just curious if it may be beneficial to try a stronger spined arrow or if it was obvious to more experienced archers that my current arrows were underspined with my current setup.

My question is why do you think you need almost 300gr on the front of your arrow? Did you drink the Ranch Fairy kool aid? That bow and arrow set up is probably lobbing rainbows.
50-75gr total insert weight is plenty when combined with a 100-125gr head. And for deer size game an arrow around 450gr is way more than enough. Hell it’s plenty for elk as well. Just some points to consider in your tinkering. I just wouldn’t go down the extreme FOC heavy arrow route with your setup.

Sorry I don't know who or what Ranch Fairy is. I simply wanted to try a heavier 500+ gr arrow and the extra weight up front was the only way I could get there with the arrows I had at the time. I ended up shooting them pretty well (for me anyway) at 20/30/40/50 yrds (range I'm a member at only goes to 50) so decided to stick with them for this hunting season. It really wasn't a trying to get really high FOC attempt, just a trying to tinker with a heavier arrow attempt. I do like to tinker though so I was thinking ahead for when I make any changes after this season and the arrow spine was a change I was contemplating making.

A spine calculator is going to recommend 300 with that much front end weight. But 350's may still fly fine out of your bow. Have you tried any paper/bareshaft/broadhead tuning?
View attachment 448124View attachment 448123

You're on the heavy/slow end of the spectrum for a compound bow with either of those arrows, which may serve you just fine if you're taking shorter shots at known distances. But you definitely have room to go lighter/faster, which would tighten your pin gaps and be more forgiving of range estimation errors. Before ditching your 350's, maybe try removing some of the FACT weights to see how much your trajectory changes. You may like it better with less weight (and it would put you closer to "optimal" spine).

Thank you very much for plugging those into your software. If it wouldn't be too much trouble, do you mind checking what it would be if I kept the 350s but instead dropped 100gr (so only 50gr weight + 14gr insert instead of 150gr weight + 14gr insert) instead? Really appreciate it!

If you are aiming for that much arrow weight, lean more on a heavier shaft to get there.

It's all about balance. You aren't gaining anything with 30% foc, if you want foc , go for 15, and have an arrow behind it that is suited to the weight range you want to be.


I think as you get more rounded in your experience, you will drop your TAW some. But if it's where you feel like you want to be, carry on.

Thank you for your input. Will prob tinker some more and drop TAW I'm sure.

 

[Rob5589]

Unless you just want to tinker, there is no reason to change arrow set up.

 

[Billy Goat]

Unless you just want to tinker, there is no reason to change arrow set up.

You think that will tune?

I suspect that much weight on the front of 350's are akin to shotgun patterns once you put broadheads on.


Now, he could definitely keep the arrows, just drop some of the added weight. I'd say 50-75 of added insert weight so it's 190-215ish on the front and it will tune fine.

 

[Mighty Mouse]

Thank you very much for plugging those into your software. If it wouldn't be too much trouble, do you mind checking what it would be if I kept the 350s but instead dropped 100gr (so only 50gr weight + 14gr insert instead of 150gr weight + 14gr insert) instead? Really appreciate it!

 

[P-Lar]

View attachment 448597

Excellent - thank you again!

 

[P-Lar]

Well after going down the arrow weight rabbit hole and playing around with the spine calculators, I ended up dropping around 100gr up front and added a little in the rear. Total weight now is 455gr. Keeping the 350s. Hopefully this will be a good mixture of weight, speed, & foc. Going to the range tomorrow to test out and re-sight. Thanks for everyone’s help & input.