Straightarrow

Most bows can be made to shoot a very wide range of spines accurately. I'm sure you can get .300 or .500 to work well. It just requires experimentation with draw weight, tip weight and arrow length. Just keep in mind that broadheads are more stable if the front end of the arrow is proportionately heavy. Heavy front ends require stiffer spine.

Build one, it's not very difficult. If you search the archives for "spine tester" you should find some info. Several have been made and posted on here. A search on the internet will also show you several sites detailing their construction. This is a gadget you can do without if you shoot aluminums. Supposedly there is a brand or two of carbons that are very consistant, but I haven't personally found one. You will also find it less necessary if you shoot a very heavy tip with a good helical fletch. They have less tendancy to plane.

AllenRead

StraightArrow,

I seem to be having problems with the bare shaft tuning. On four different sets of arrows, I nocked & pointed six arrows and then fletched three of them. I started with the arrows uncut.

They all seem to shoot to the same point of impact, even though, according toOnTarget, they are grossly underspined. They are well into the red on the weak side.

One specific example:
Arrow -Carbon Express CXL2 150's - full length - 180 grain points - fletched arrows 3 feathers - 4"
Bows - Mathews Icon & Martin Scepter Nitrous X - both set at 25 7/8" & 48 #'s
Release - Zenith hinge

All arrows fletched and unfletched shot to the same point of impact, at least to my level of skill, from 10 yards to 60 yards. I was getting normal groups for me. It did not seem to matter if the arrow was fletched or not.

Am I doing something wrong?

Thanks,
Allen

Straightarrow

It's not just where they impact. You need to look at the angle they enter the target. If they are not entering at an angle similar to the fletched shafts, then you need to experiment with spine adjustments. If they are all entering the target straight in, then maybe spine isn't off that much. I've shot weak bareshafts that fly almost sideways on the way to the target.

If your fletched shaft's spine is off a mile, then it will not hit where it should either. You may want to cut off an inch or two on one of the fletched shafts and then retest. Just don't cut off more than where you expect it to end up. Your archery program should be able to help you with that. I always try to use a shaft that I expect to be a bit weak at full length to start with and then cut it down until it flys perfect. Too many people want to shoot the shortest shaft they can, regardless what it does to spine. I don't care if mine are 32" long. I shoot them at the length that gives me the correct spine.

I'm fortunate. The shop I go to, has all it's popular shafts available to test, cut to different lengths (1/2" increments). They're available bareshaft and fletched. I'm able to grab several different tip weights in the range I want to shoot and try them on several different bareshaft arrows, compared to several differnt length fletched shafts. After having done this many times, I know approximately what I'm going to need. For someone, who is doing this for the first time with a particular shaft, it may take a bit of experimenting.

AllenRead

StraightArrow,

Thank you for your reply. It's obvious that you spent some time & effort on it & I appreciate it.

I'll try your suggestions.

Allen