Will similarly spined arrows shoot the same?

[MnFn]

Specifically, would 400 FMJ shoot the same as 2117 at the same length?

[Wudstix]

I’m thinking it would depend on arrow weight being close or not.  Guessing 2117 would drop a bit quicker.
 

[McDave]

My experience is no, similarly spined arrows will not always shoot the same.  I have had the experience more than once of solving a vexing tuning problem by changing to a different shaft with a “similar” spine.  I have also had the experience more than once of changing to a different shaft with a similar spine that seemed to shoot the same, so “it depends.”  I think the reason there are sometimes differences between similarly spined shafts is that the real differences between similarly spined shafts are sometimes greater than the differences we commonly use in tuning arrows such as trimming the length or changing point weight.  Heck, I’ve even had significant differences between shafts from different batches that are identical in brand and spine.

[Alexander Traditional]

I need to buy a spine checker. You can get Gold Tip,Carbon Express,Beaman,and aluminum that are all supposed to be close in spine,and they will all shoot differently. I think if you bought anyone of those though,and they were close in spine you could make them work.

[MnFn]

Thanks for the replies.

I have a new bow I am trying to get arrows tuned for.  By using 3Rivers calculator and talking with a fellow bow hunter I  found 2117 to be a good starting point, with enough weight.

I also dug out a FMJ 400 to take along. I didn’t have much hope in them because I thought they would be too stiff. They have been cut down to 29 “. However,  with 200 grain heads they shot very well right from the start. Very happy with them.

I didn’t want to use FMJ, because of the cost, but I may have to if the 2117 don’t shoot as well after tuning them. Hopefully they will be close enough. I haven’t started shortening them yet but at full length bare shafting they are way too weak.  The shaft weight difference maybe a problem. We will see.

Thanks again
Gary

[Wudstix]

Think 2117 spine at 77.4# if that helps
 

[Orion]

.400 spine is about 78-79#, according to Easton's way of measuring.  I have a chart that says xx75 2117 spine at 81#.  Pretty close. However, they may or may not shoot the same.  Carbons tend to recover a little faster, and I'm pretty sure the FMJs are smaller diameter, which means they ride closer to the center of the bow, enabling the bow to accommodate a stiffer spine.

Looked at another way, if two arrows are spined identical, but one is larger diameter than the other, the larger diameter shaft will act stiffer when shot (out of the same bow).

[6feathers]

should be close but the only way to find out is to try them. the 2117 will probably weigh more.  good luck

[katman]

I found if shaft weight and or diameter are different the same spine won't tune the same if length and point weight are equal.

[Friend]

Possibly, but not likely…far too many variables…even same spined shafts from different manufacturers may not tune the same. Example: 400 spine shafts…one manufacturer may have their process tightly centered at .380 and another manufacturer may have their process tightly centered at .420….identically setup arrows will likely mark noticeably different when tipped with the same broadhead.

[MnFn]

I am very close to being done tuning aluminum 2117. I think one, maybe two more cuts.

400 FMJ 29 1/8”  with 4X5” fletching,  and 200 grain heads  weigh about 605 grains fly very well. I can’t remember what I put in there for inserts ( I’ve had them awhile); I guess I’ll have to take it apart to see so I can replicate it. I have not shot a bare shaft yet. Will do so.

2117 cut down to 30”  4X4” fletching with std inserts and 200 grain heads fly pretty well, but same arrow bare shafts weak. Probably end up at 29.5 or 29.75.
Current weight is 610.

My only real concern now is how heavy they are.  It’s a 50 lb recurve, so about 12 gpp. I tend to shoot a little low with it, so I’d have to reprogram my brain. But I guess I could use it for about anything around here.

[Wheels2]

I never could get such.
Arrow material (carbon vs aluminum), shaft diameter, and shaft weight all affect flight and tuning for me.
Now if I adjust centershot to compensate for the arrow diameter, I get get better results except for tail kick due to diameter and resulting nock height.

Using the newest Stu Miller dynamic spine calculator, I can determine  a very probable match based on a know combo that works for me.  I.e., dynamic spine needs to me 92#, then I run combinations until I get that same result from a "Possible".

[BAK]

So it appears the definitive answer is "maybe".