3D4PSE

Big Country,
That is exactly how people come up with the crazy numbers on Jackson's site. You have to know how to properly enter the information before it can spit out he correct info. I have had people tell me that the FOC on a given arrow was anywhere from 7% to 10% just because of the numbers they punched in when we were referring to the same arrow.

Shan

I just measured my Goltip 5575's. They are 28" from the throat of the nock to the insert. I also just lowered my poundage to 60# (for spring turkey hunting). I shoot a 100 gr. muzzy broadhead. If I read the chart right I am a little on the stiff side for my setup. So, theoretically I suppose the spine issue shouldn't be the root cause of difference in impact points between the field points and broadheads.

I paper tuned bullet holes with field points and broadheads. But I still have broadheads striking 6" lower than the Fieldpoints. First of all, what is the cause of this. Secondly, if it is fletching contact (I shoot feathers)does it go away with the MZE???

3D4PSE

It is caused by the 'wings' on the front of your arrow are trying to control your arrow flight and the fieldpoint aren't. The filedpoints require more rest movement than the broadheads to make a point of impact change. Therefore, if you bow is tuned, very slightly move your rest up and try shoot the broadheads where the fieldpoints are hitting. Once you get this done, you broadheads are flying as good as they can because they are flying just like fieldpoints. I do not go to alot of trouble on this if I am getting real good groups without them hitting the same but I have done it a few times when I got bored or really nervous about a big hunt. Let us know if it fixes your set up.

Len in Maryland

The way I've read these posts on the spine chart differential, I'd say we're all equally right and wrong in our convictions. After all, the charts are only an "indicator" for the correct spine for your individual bow/arrow system.

Because the charts are indicators, in my shop we use at least two of them plus the manufacturer's chart to ascertain where we should START. I can't tell you how many times the charts were incorrect. After all, how can a chart cover all the cam styles, limb deflections, and string elasticity. Now keep in mind that we're talking about getting something fine tuned.

We've had situations where we tried three different carbon arrows from three different manufacturers while using their individual charts for the selection for a particular bow. One might work to perfection whereas the other two fell far short.

What this is all getting to is that there are a lot of things that affect the arrow selection and minor discrepancies can put one "over the edge". By moving the weight outward by any type of "extension", you can weaken the spine. For example, a 1/4" round ball at the end of a straw will not have as much impact on the straw as a long 1/32" rod weighing the same weight as the ball. That "length" will affect the spine; but, by how much??? We must also consider the fact that the blades of a broadhead are wings that can drive the spine in any direction on a poorly tuned arrow.

If you are close to the edge of spine discrepancy and you extend the length of the weight, it could affect the spine. If, on the other hand you are at the mean spine parameters, the affect will be negligible.

3D4PSE

I agree but it does not change it enough to even consider it. If you spine is right for fieldpoints of one weight, the broadheads will have a sufficeint spine unless you shoot a 5" long broadhead that has a 3" cutting diameter. We are nit picking.

Len in Maryland

If you put a 2 1/2" Steelforce or Magnus on the end of an arrow, it can very well push an arrow off the necessary spine. Yes, this may seem to be nit picking to you; but, there is a reality to this under certain circumstances. And, when it pops up, we must be aware of the probable causes and probable solutions.

3D4PSE

OK, I give. I am not going to convince you and you are going to convince me. That is what makes archery fun. We can both believe different things and we both can still shoot good.

Edited by - 3D4PSE on 02/09/2002 00:29:27

Big Country

Even I will agree that a head that is of that length, can affect arrow spine. Who uses that stuff, anyhow!
Hey 3D4PSE, this is just an opinion on my part concerning the jackson chart and FOC.
If someone knows enough about archery to even care about FOC, why would`nt they just figure it out themselves?

FLHunter

Big and 3D,

I understand what you are saying, but from a practical standpoint just a little extra total arrow length can change the spine of your arrow. For example I had a set of arrows whose spine was supposed to plenty adequate for the poundage I was shooting. In fact I was about 8 pounds of drawweight below the charted spine limit of the arrows. When I added the same weight broadhead to the shafts(100grain)the arrows would not group with my field points at the same poundage. Backing off the draw weight 3 pounds allowed the broadheads to group with the fieldpoints. Take the broadhead back off the arrow, push the poundage backup and the arrow would group in the same spot, or leave the lower poundage add the fieldpoint the arrows would group with broadheads. The arrows were spin tested for being true. The only factor that changed was the arrows total length by adding the broadhead. The flex nodules of the arrow had changed with the slight difference in the length of the arrow.

Aim Hard!

Shan

FLHunter, Len, 3D4PSE and others,

Do I take the above posts to mean that the MZE will cure the "contact" issues between the arrow and rest but not the spine isse (which perhaps is the real culprit in this dilema)? Again, in my situation Goldtip 5575's @28", 60#, solocam, release/loop what other choices do I have??

Is moving the rest up to meet my fieldpoints as 3D4PSE suggested addressing the spine issue or merely just treating a sympton. And how big an issue is it really. Or put differently, how much does this affect accuracy?



Edited by - shan on 02/09/2002 12:00:06