arrow spine. 400 too weak?

5MilesBack

Well Known Rokslider
Joined
Feb 27, 2012
Messages
13,852
Location
Colorado Springs
A lot of folks have successfully used weed eater line inside their arrows to add some weight. But when you're standing there holding onto 50gr of line you really start to wonder whether "that light of weight" makes a hill of beans difference whether the BH and arrow still blows through the elk without it.

Oh, and I'd make sure you did your own BH tuning. "Your" grip makes all the difference in the world.
 

Mighty Mouse

Well Known Rokslider
Joined
Jun 21, 2019
Messages
1,569
Location
Oklahoma
They took my bow and showed me the center shot was slightly off so I left it with them to fix that and broadhead tune.
Letting the shop tune your bow is okay for a starting point, but you need to be the one shooting to confirm/finalize the tune. Differences in grip, anchor point, etc. can affect how a bow tunes. Your bow may or may not need to be at the manufacturer's recommended centershot (usually 13/16" from riser to centerline of arrow) depending on the lateral position and/or lean of your cams (as well as other factors).

I'll probably go back to my 340's just so I don't have the thought of an arrow splitting on release bugging me.
Spine charts/calculators will all say that 400 is on the weak side at your specs, but you're not at risk of the arrow actually failing. "Too weak" in this context means the arrow will bend more during the shot than the estimated optimal amount of bending. It doesn't mean that the arrow is structurally weak and at risk of breaking.
 

Lowg08

Well Known Rokslider
Joined
Aug 31, 2019
Messages
1,693
Letting the shop tune your bow is okay for a starting point, but you need to be the one shooting to confirm/finalize the tune. Differences in grip, anchor point, etc. can affect how a bow tunes. Your bow may or may not need to be at the manufacturer's recommended centershot (usually 13/16" from riser to centerline of arrow) depending on the lateral position and/or lean of your cams (as well as other factors).


Spine charts/calculators will all say that 400 is on the weak side at your specs, but you're not at risk of the arrow actually failing. "Too weak" in this context means the arrow will bend more during the shot than the estimated optimal amount of bending. It doesn't mean that the arrow is structurally weak and at risk of breaking.
It would constitute a possible failure if the arrow was compromised and under spined. If that makes any sense. It would multiply the possibility. Some arrows are compromised and pass the pre shot test on an arrow. May even be shot multiple more times. Hypothetically the arrows could pass pre shot testing but explode in the face of the user if under spined. Just a possibility rather than a definite.
 

Jethro

Well Known Rokslider
Joined
Mar 2, 2014
Messages
430
Location
Pennsylvania
Have the techs at your shop killed a pile of elk with their bows? If the answer is “no”, then what they use and recommend is irrelevant.

Even if you get the 400 spine to fly and tune, I’d choose the 450g arrow for elk.
 

BigSky

Well Known Rokslider
Joined
Jul 31, 2012
Messages
1,431
Location
Billings, MT
Others have touched on most of the salient points. In my opinion, almost every arrow spine size, up or down one on the charts CAN be made to work. My thought is usually, 'why do it?'. Using the correct spine from the recommended charts will only improve accuracy and tuneability. Offer up some of your 400s for trade on craigslist and here. You'll find some. Heck, I even have a couple of dozen excess 340s sitting around for/from other bows I no longer have. I just think you will be way ahead in overall performance with the correct spine. Oh, and 400s have probably killed as many elk as have 340s, in the "proper" bow. Good luck in your quest OP.
 

Kolt45

Newbie
Joined
Jun 15, 2022
Messages
3
I've been shooting 400's at 70# 29.5" for several years and they have never blown up but the do do weird stuff inthe air. Recently switched to 300 and the fly much better
 
Top