Arrow length vs draw length

[lanemj]

I'm a new shooter and I purchased a Mathew's V3 31" and when I took it from the shop they had me set up with a 29.5" draw @ 60# with Easton Axis 5mm 340s cut to 29.75" (when i'm in full draw the tip of the arrow is just a bit in front of my index finger - in other words, the length seems right, i.e. a BH clears my finger, but barely).

Now, I recently bumped my draw weight up to 70#, but all other variables remained the same. I noticed on 2 of my arrows the carbon had started to flake off the arrow on the shaft and all the arrows seem to be flying funny, but only very slightly. I mentioned this to a buddy who told me 340 grain isn't stiff enough for a 29.5" arrow at 70# pullback. Easton's arrow buyers guide re-enforces his belief.

My question is this, do I need a 300 grain arrow with a 29.5" arrow and a 70# pullback? If so, would the FMJ Legend series at 300 grain do the trick if I'm aiming to get close to 500 grains for elk season? They're about 12 gpi which, with a 125 g BH, would put me at 482 g not counting nock and fletching.

Obviously there will be a lot of experimentation as I try to dial in the FOC and arrow weight that flies best, but I really want to get my shaft right.

Ps, I'm not tied to FMJs.

Thanks in advance.

 

[Billy Goat]

The axis uses a hit system. If your point is just slightly smaller than the shaft diameter than you are exposing raw carbon ends which can then be pulled off.


I'd go heavier spine. The number on the shaft isn't grains, but the spine deflection.

 

[Zac]

If it were me I would go back to 60 and use the shafts you have. They are junk if you go up to 70. They are probably on the light side for elk, however you could put a very efficient broadhead on the front and probably do just fine. Another option is cutting that shaft you have down from the back. You could probably shoot close to 70 lbs with a 27.5 inch shaft. If you decide to go to a 300 spine you could use an FMJ. However you could make up that weight by simply using a 50 grain insert in the Axis. Since you are new you are going to blow up those FMJs quick.

 

[Mighty Mouse]

The carbon flaking issue isn't really related to the spine of the arrow. 340 spine may be weaker than optimal (i.e., flexes too much during the shot) at the length/draw weight/point weight you want to shoot, but not so weak that the carbon will fail during normal use. The flaking you're seeing could just be from one arrow grazing another while shooting groups, or maybe a point/shaft diameter mismatch like Billy Goat suggested.

 

[Shawn_Guinn]

I would shoot at minimum a 300 spine and cut it as short as possible I mean as close to the rest in the up position as possible and consider 100 grain heads. If you want to keep the shaft in front of your hand which some people still do I would move up to a 250 spine especially if your want to use 125 heads. Then just cut them to 31 inches and shoot away.

 

[5MilesBack]

Another option is cutting that shaft you have down from the back. You could probably shoot close to 70 lbs with a 27.5 inch shaft.

I'd cut it down right off the front which would take the insert off as well. Put new inserts in (50gr HIT's would work great) and then tune the bow to that and shoot the heck out of them.

 

[gelton]

You could also take a turn out of both limbs and lessen the draw weight. I have found by monkeying around with Archers Advantage that the biggest factor to trying to bring an arrow back into spine is draw weight...much more so than arrow length.

An example for me shooting a V3 @ 28.5" and 70# it showed a .300 spined BE Rampage as slightly stiff if cut to 27.75" and even if the arrow was 28.5 inches it barely moved the needle to bring it back to optimum, but if I put in the actual poundage which is 70.8#'s it brings it right to the middle. (keep in mind I am shooting 4 fletch and lighted nocks)

So less than a # of draw weight did more than 3/4" arrow length change (at least according to AA).

 

[Zac]

I'd cut it down right off the front which would take the insert off as well. Put new inserts in (50gr HIT's would work great) and then tune the bow to that and shoot the heck out of them.

That may work, although you may ruin your progress with that much weight. Best option would be to get different point weights with a hot melted standard insert. After you figure out your point weight then you can match your insert and point to get to whatever combo you want. Someone with Archers Advantage can probably get you close.

 

[5MilesBack]

That may work, although you may ruin your progress with that much weight.

We're only talking about 34gr here.......that's nothing, especially after lopping off 2.25" of arrow, which really is a big difference when it comes to spine. I'm pretty confident that I could easily tune to those 340's with 50gr HIT's at 70lbs, even with my 32.5"+ draw length if I could get the arrows that short. Even with 30" arrows I'm sure I could get it pretty close.

 

[Zac]

We're only talking about 34gr here.......that's nothing, especially after lopping off 2.25" of arrow, which really is a big difference when it comes to spine. I'm pretty confident that I could easily tune to those 340's with 50gr HIT's at 70lbs, even with my 32.5"+ draw length if I could get the arrows that short. Even with 30" arrows I'm sure I could get it pretty close.

Yeah you're probably right. He could always lower his poundage a touch if he was on the edge. Kind of odd the shop didn't set him up with 300s. I've never known anyone that has the patience to stay at the same poundage.

 

[zr600]

I had the same thing happen. Shop set me up in 340s and I couldn’t get a good consistent tune. I’m like 30” draw I don’t remember how long my arrows are. This was with my bow set at 65lbs. So I got some 300 gt velocity xt made them up and bam got my tune perfect. Now remember if you time your bow and change anything, draw length or weight, new arrows that are a different brand/weight can all change your tune also. Good luck gold tip has some good tuning videos online too.

 

[Paridgerunner]

Yea your under spined

 

[PNWArcher82]

Im The same draw length and arrow length as you.
Shop also set me up for 340, which was dumb as I increased weight up front and draw weight.
Also, I’m using 29” mods as Mathews tend to run long. Just something to keep in mind.