This procedure will help you find the proper length (balance point) for your custom ammunition.
Attach the head to the shaft using whatever means you plan to use. IE; hot-melt and steel bodkin. For SCA combat standards.
Make 4 ,all of them longer than you think it should be. Do not fletch the shafts at this time. Put one arrow aside.
My procedure is as follows:
Pick a calm day.
1 Shoot all three rounds, and observe their flight. An arrow that is balanced way too tail heavy, The tail will follow the tip at a lower elevation and land tail first or sideways.
2 Cut 1 inch off the tail of the shafts and shoot again, observe their flight. You will notice the same problem but less intensity.
3 Cut and shoot again and again, until you notice that the arrow's tail snaps
up like a whip prior to
the apex of flight. Record this length. Set another arrow aside.
4 Continue to cut and shoot the other two arrows, until the tail follows the tip through the apex straight and true. I call this the "best apex" length. Measure this length (for instance 47'') and cut a saved arrow to 1'' longer. Cut another arrow to 1'' less. And the other saved arrow to 2'' less. IE 48'', 47'', 46'', 45''.
5 If you plan on using any nock design, do it now, and shoot a volley of various lengths and observe the change in flight. If it is drastic then you may need to adjust the various lengths, most likely shorter.
6 Attach a fletching design of your desire to the whole batch, and shoot them. Did they fly well, or flap like a pigeon? If they are pigeons then try another design on the whole batch, If good, then record the length and fletching style, strip them, and try another design on the whole batch. Try a bunch of ideas keeping records of the good ones for a comparison round. Hint: put the fletching on crooked so that it will spin.
7 Make two arrows to each of the good style and length combinations. Shoot them all three times. Pick the best and make and batch of matching ammo. Feeling Picky? Modify the shape and size of the best fletching style (IE a cut here, a bevel there) and check again.
It's sounds like a lot of work, but I did it in one 10 hour day.
Adjusting the length of the shaft improves the overall flight line which gives better penetration and harder hit and adds accuracy.
Fletching an arrow adds stability and resistance to crosswinds. Spinning an arrow increases that ten fold.
The arrow should begin to spin within 1/4 of it flight. (IE 30 feet off the weapon). Sooner is not bad, but it will drag down the max range of the round. Too late (IE at or just before the apex) and accuracy will suffer. To add spin, increase the surface area of the fletching, To lessen spin decrease the surface area.