DeerT

I shoot a Bowtech TomKat at 60lbs
27" draw
I currently shoot Beman ICS camo' s (400' s) with 100 grain head.
My questions are: Is this spined correctly for my set-up? I don' t think so but I' m not sure. What if I went to an 85 grain head?
Would changing to Winner' s Choice string have any effect on the arrow needed?
Finally, does the Bowtech TomKat use what is considered a " hard" cam?
Thanks in advance! I know you' ve seen these questions before but I just can' t seem to find the answer to these questions as relating to my bow/draw length/draw weight. Thanks again.

CBM SC

Your overspined, but a lot of guys on here say that' s good/better on Bowtech' s . Your cam would be considered a hard cam. Your string wouldn' t make a difference . If your arrows are shooting good don' t worry about it !

c903

You have not really said why you believe your shaft spine is incorrect. However, your setup appears to be at the very minimum settings e.g. draw length, Draw weight, let-off (You do not say but can make a difference), etc.

I do not shoot carbon, but according to the charts, you appear to be over-spined. Dropping the weight of your head from 100gr to 85gr will make matters worse if your are already over-spined. Can you crank your draw weight up, or is 60lb what you can best handle at this time?

Add to the picture, you are shooting short shafts off a short ATA bow. Are you experienced/skilled enough in bow shooting to handle the sensitivity of a fast and short ATA bow?

I don' t ask this question to be condescending; it is important to know your experience and skill with a bow, and to know how much you know about tuning and recognizing what might be causing certain problems.

As CBM said, it appears your cam is a hard cam.

c903

I wanted to respond to your question first. Now I want to respond to something that CBM SC said regarding arrow spine. CBM did not say he agreed with the statement, he only stated what others have said.

There is no such thing!

An arrow is either perfectly matched in spine to bow setup, or it is not. You can sometimes get an over-spined or under-spined arrow to fly good and to hit the mark by number of feather/vane, size, and type used; and by tweaking other gear, but such a setup will always be at the edge of the envelope, inconsistent in performance, and extremely vulnerable to the slightest mistake in form, release, and certain environmental forces.

If some Bowtech shooters are getting consistently good flight and good accuracy out of arrows that are over/under spined, those shooters are doing something that is compensating for bad arrow performance, and they may not realize they are. Or, the shaft selection chart vs. the setup they are using is incorrect.

Remember, a shaft that is under/over spined, and is having its flight being corrected by other means, may be trying to swap ends and is loosing speed down range. Also, contact angle on quarry may be off from center and cause decrease in penetration.

pdq 5oh

DeerT, Beman' s chart suggests a 500 arrow at 55-60#, 27" long. A 400 is suggested at 60-65#. I don' t think you are over spined. What gives you that impression? Try a 125 point & see if anything (other than point of impact) changes. Do you start hitting left or right. Are your groups opening up as you move back? By that I mean starting to get flyers.

The BowTech bows, in particular the dual cams, do like a stiffer arrow than the charts suggest. I think this is due to the aggressive cams. When a 60# BowTech is shooting 320 fps, and a similarly speced bow from another manufacturer is shooting 290, the BowTech is obviously imparting more energy into the arrow. For this reason, a stiffer arrow is needed with the BowTech. The single cams are not as in need of the stiff arrow, but do to a degree need one.

CBM SC

I' m saying overspined because he probably is shooting a shorter arrow than 27" (since his draw is 27" ) , I may be wrong . A 25" or 26" @ 60-65 # calls for a 500 ICSCH .

So we need to know the arrow length !

And yes I am just posting what I' ve heard , I don' t have a Bowtech.

c903

pdq 5oh

In other words, the selection chart, as is the case with most selection charts, is general -not specific.

What some shooters do not understand, is that regardless of charts, regardless of the energy the final setup of the bow is imparting, there will always be a need to have a perfectly matched shaft spine.

If a bow tends to shoot a arrow better with a spine that is less or more than what the chart indicates, it is not just the variance of the bow/setup that supersedes or subordinates what the chart says, it is that the selection data is too general in order to find a mean for all bows and setups.

Without further info, it still appears that " DeerT" is so close to the cutoff, his arrows may be over-spined, or so close to it, he needs to add weight to the shaft or pump his draw-weight in small increments.

On one of my bows, shooting 31-5/8" 2315 shafts w/125 grn head, the chart indicates that I can use a draw-weight of 59#-64#. After finally finding the perfect draw-weight to shaft, I cannot use 1/8th turn less or more than 62#.

DeerT

Thanks for all the input. I knew you guys could help. Sorry I didn' t give enough detail in my first post.

My limb are 60lb-they can be cranked up to 64 but 60 is comfortable for me.

The reason I submitted the question was that I had 70lb limbs on the bow when I purchased it. I did pull 71lbs for about a month and decide it was just too much bow for me. I' m 5' 6' ' and 130lbs so I don' t think I will ever want/be able to comfortably pull 70lbs and after reading/researching lots of info on the subject I don' t think I need to.

The 85 grain head was just what the Pro shop guy recommended-I' m sure it' s because he' s after speed-which I' m not nor can I be with my draw length and draw weight.

I looked at the Beman chart and I seem to be on the fence for either the 500 or 400. So I' m a little confused. If I have the right shaft...great.

I am getting a few flyers(usually to the right) when I get out to 30 yds. Everything is right on the money 25yds and in. I know this could very well be the shooter but if it' s not what would be your suggestions.

I just want to get the correct spine for my arrows so that this can be one less thing I know couldn' t be a problem. I' m not confident in my knowledge to tweak my own bow so I usually go to the Pro shop. Thanks again for you input and keep it coming.

CBM SC

If your not worried about speed , then I think you can go to a 125 grn head and be spined correctly, but lose about 8 fps.

c903

Pdq 5oh may have it right on this..." Why do you believe your overspined?"

Are you getting occassional " fliers" to the right, or are you impacting to the right?

Impacting to the right can be indicative of underspine. Impacting to the left can be indicative of overspine.

Being your accurracy and grouping is good up to 25 yards, I would leave the shafts as they are for the time and look for other causes. If you were consistently going right at all yardages, of the many things I would check, would be the centering of my rest. Also, check and see if your are " canting" your bow.

Ah, archery! Nothing better if one craves confusion and frustration!