Straightarrow

Arthur, Ashby has written so much, it's difficult to remember everything, but I did find this that he wrote.

"Data was suggestive that shaft diameter did appear to be of significance in penetration. When velocity, broadhead and arrow mass were constant, shafts (1) smaller than the broadhead ferrule in diameter, (2) equal to the broadhead ferrule in diameter and (3) larger than the broadhead ferrule's diameter did appear to be a significant factor in penetration. No difference was discernable between shafts of varying amounts smaller than the broadhead's ferrule. If the smaller diameter shafts are assigned a factor of 1.0, then the apparent reduction in penetration was 10 percent (0.9) for shafts equaling the broadhead's ferrule diameter and 40 percent (0.6) for shafts of diameter exceeding than the broadhead's ferrule.

With a quick look, I couldn't find anything else that contradicted this. It appears that his studies had to do with the relationship between shaft size and ferrule diameter. The thing about the small diameter shafts is, it is easy to find broadheads with larger ferrules. In fact, I don't think you can find otherwise.

Kanga

Yes I could, but that would open up another can of worms because the arrows are currently spined for the heads and if I swaped heads then I would have one arrow over spined and one under spined


That is true and I totally agree but my tests where for mainly arrow flight and to see what the drop was between the 2 arrows I was expecting the heavy head to drop but was surprised when it didn't.Oh and the human element was taken out of the shooting

Unfortunately no I dont but I do plan on going after some again when the weather cools down.

Arthur P

Ashby had posted a preliminary chart in a thread over on Tradgang.com that showed average penetration for a variety of arrows using the same broadhead. I think it was GoldTips he'd weighted up to 600+ grains, to be equal to the larger diameter arrows he was using. Don't remember the brand for sure at this point. Anyway the carbon arrows did penetrate better. Not much better, only a couple of inches, but it was measurable and consistent.

I kinda drew my own conclusions from that. It may well be the shaft dia. vs the ferrule dia. is what makes the difference. I'm not sure Ashby himself has reached a firm conclusion yet. But it's obvious to me from his data that, using the same broadhead, a smaller diameter arrow shaft at the same weight with the same FOC will yield at least somewhat better penetration.

Doesn't mean I wouldn't still poke a hog with a 2315 or a 23/64ths cedar though. They've been doing great for me for a lot of years. It's just that I've still got a lot of crow left to eat over this shaft diameter thing.

Straightarrow

I agree that diameter most likely has an effect. I was just trying to find if there was any hard evidence of it.

I know what you mean. I'm totally convinced on the benefits of extreme FOC arrows, yet I'm going to be shooting some 2018s with only 125 gr on the tip, out of my longbow this fall. 560 grains that flys straight, will still do the job on a deer. I have the arrows and they are too weak for a heavier head, but they have plenty of deer shooting left in them.