I just got myself a grain scale and in my excitment of wanting to try it out, set out weighing items in my archery arsenal. I always had a fairly good idea what my finished arrows weighed, but never knew for sure. It turns out my guess was pretty good. The next thing I set out to weigh was field tips and broadheads. The field tips weighed out fairly good, with only a 1 grain +/- difference from the weight they were supposed to be. The broadheads were another story. For the replaceble blade heads I weighed (Rocky TI 100s and Ironhead 125s), I weighed each ferule with the same set of blades and washers. I recorded a +3/-2 grain variation from the stated weight for these two brands of heads. Thats a difference of 5 grains between the heaviest and lightest heads of each type! I also put some complete 125 grain Rocket Steelheads on the scale and had simular results. This got me thinking, if itty bitty broadheads are this bad, how bad are my arrows? To my relief, my ICS Hunter shafts (with nocks and inserts) only had slightly more than a 1 grain total deviation between the 8 that I weighed. This leaves me with two questions. If carbon arrows can be manufactured with such good weight tolerances, why can't something as simple as a broadhead weigh what its supposed to? Secondly, and more important, how much weight deviation in a broadhead tipped arrow does it take to start seeing a difference in your groups at hunting distances (let's say 40 yrds or less)?

Olink,

From target archery I can tell you that as little as 3 grains or so can make over an inch difference of impact height at 60yds. When building arrows I always weigh components and adjust them to make my arrows match up within a half grain. I was building up some aluminum arrows for my recurve not too long ago and its amazing how inconsistant parts can be. I found anywhere 5-7 grain variances in inserts. Tip weights vary 5-6 grains at times. Even nock adaptors vary in weight. Aluminum shafts often vary several grains within a dozen. Its a tedious task to sort all the components to try mateup the best combinations before removing metal to bring the weights in. For the most part I use all glue on components like nibbs, field points, and broadheads. The consistancy seems to better in the manufacture. It is possible to have arrows that have 10 grains or more difference from others within a dozen if just assemble your arrows without balancing things out. At short ranges like 20 yds most archers would hardly tell the difference. Stretch the distances out and the story changes. Once I get my broadheads weighted and tuned they remain broadhead arrows only and stored as such for the next use. Its too much of a hassle to go through season to season tuning them.

I can't speak to high speed wheel bows, but there have been studies re traditional bows that indicate at normal hunting distances, i.e. 20yrds or less, arrows can vary as much as 100gr with no noticeable difference in point of impact. However, arrow straightness has a much higher affect on accuracy. As a consequence I keep my cedar arrows within .003 straighteness and could never understand why some would tolerate carbon arrows no straighter than .006
Of course at distances longer than 20yrds, weight variance begins to play a much larger part.

Jack