Easiest Carbon Tune EVER!

[JR Williams]

So last week I got a new Thunderstick III from Jim Reynolds, it is a cut to center 66' 50@28 and I draw it to 28 in. It has an 8 strand SBD string on it with wool silencers and I put a calf hair shelf and plate on it.

When I ordered this bow I had a gift certificate and I bought a dozen Beman MFX 400, I wanted to shoot 250 gr points so I figured this spine would put me in the ballpark. My goal for arrows was to be 12-13 gpp, with 20 % FOC so I figured that I would use 250 gr points and 50 gr inserts, start full length and cut down until they fly straight.

 Took a long lunch yesterday and went to my local archery shop. I was gonna shoot and use their saw to cut down as needed. Anyway, I got all set up with 2 bare shafts and......

These things flew like darts! I mean PERFECT. I spent about 45 minutes just having a good time shooting the bare shafts, I also had brought two fletched shafts without inserts, so I put inserts in them and points and they were all grouping together at 25 yds. I have never had it so easy with tuning.

Now I figured that they would need to be cut down some, I am shooting 32.5 in arrows but as long as they are flying straight I don't care.

 When I got home I put in the arrow info into Stu's calculator. These arrows are showing a dynamic spine of 31 Lbs. Now in this case I am gonna believe the bow, but I was really surprised at how far off it was from my bow on Stu's. My bow shows I need 54 lb spined arrows.


 Anyway, I am super happy with my tuning, I must have been living right lately.

[JV Rooster]

[AdAstraAiroh]

Stu's calculator is but a frustration for me.  My data measurements and imputs are exact, and yet the spine matches/recommendations for different bows have been plus or minus 15 pounds outside of the tune established by bareshafting and paper tuning.  My latest 40# longbow has a bow output calculation of 48.4# (.500 spine) but bareshafted perfectly at 58.2# (.400 spine) I double checked every measurement. When the .500 spine was bareshafted with 80 grain point, it was so weak it flew completely past the right side of a four foot target, tail flapping all the way.  I believe that for each bow, string, and arrow combination it is completely unique, and then specific to the archer and his form. Real world tuning is the only best bet.

Mark

[JR Williams]

Mark,

 Completely agree, the bow does not lie, it will tell you what it likes. I also tuned an ACS CX a few weeks ago. When I was done I placed the info into Stu's and it was pretty close, I was very surprised this time at the difference. It was VERY different. I do not use Stu's calculator for tuning, but I do play with different combinations on it just to see the differences.

[JR Williams]

Mark,

 Completely agree, the bow does not lie, it will tell you what it likes. I also tuned an ACS CX a few weeks ago. When I was done I placed the info into Stu's and it was pretty close, I was very surprised this time at the difference. It was VERY different. I do not use Stu's calculator for tuning, but I do play with different combinations on it just to see the differences.

[awbowman]

Jim makes a great bow.  Love my Mag

[daveycrockett]