Ozbow

so i'm trying to make a set of hunting arrows.

in order to have heavy arrows i'm using 100gr weights with 160gr heads.

the bow in question is an uncut horsebow, probably .4" off centre, with a 14 strand 452x
it is #50 @28 but only drawn to 26-27. thinking arrows need to be about 29"

so the number i've come up with thanks to some help from 3 rivers spine calculator is #65

i expect the mass should total 700+gr [with oregon]

65 was the number i had imagined before using the calculator too, which is nice. but i'd like to know if that sounds too high?
#65-70 were the shafts i figured would be ideal...

any thoughts would be great, thanks

i think i'll be aiming for 60-65 on further thought.

http://www.janynfletcher.com/Arrows_New.html

i found this to be the most useful article out there, and the author thinks that under spine is more effective than over spine.

what i found to be interesting was that the GPI of the arrows change accordingly with spine strength, which must cause the arrow to weaken its own spine slightly at the upper limits. so sudden jumps up in spine seem to be required to make heavy arrows, but i may have jumped a tad too high.

also, on the topic of draw length. is the actual average 28? or less

i draw to 26 and i'm 5'11"
i the above article would imply i'm not drawing adequately with my shoulders perhaps, but i'd like to know if the 28 average is an overestimate, because my friend who's a little taller than me still has the same draw length at 26, perhaps 26.5 or some small difference

Hi,
You say you are shooting a horsebow with no shelf, so I do hope when you read the chart you looked at as selfbow information and not recurve.
Re your draw length, if you are "leaning into the shot" then your draw will be a little less than if you stand bolt upright. If you however, are already standing bolt upright, then something may be amiss, or perhaps the bow is little heavier than you believe.
These are just some observations, in my opinion, based on the information you have provided.

cheers
sue

I've had reasonable success getting arrow to fly well using Stu Miller's spine calculator. Hope it helps.

http://www.heilakka.com/stumiller/

Cheers.... Rod