What weight is considered a heavy arrow

[Knoll]

A 10gpp setup has high odds of ethical kill if impact is in sweet spot.
But, as you say Ed, with setup you describe ya have good odds of kill even if it's a not so sweet spot.

[BowEd]

Yes your right knoll.Your talikng in a perfect world with a perfect shot though.Many times it just don't work that way.Deer are still awfully tough critters running at 90% nervous break down while cruising the woods.Always on the alert.A foul shot most times is an investment into a long drawn out retrieval.It's still all about putting an ethical clean shot through the heart/lungs/or liver or all three at the same time and heavier arrows put the odds in a hunters' favor.The vitals on a deer are actually bigger than what these 3D forms show.Proper angling of shot is super important.Lots of variables.One reason why it can take a lot of patience to get that perfect standing shot while the deer is mostly relaxed and without spooking the deer.Probably why I've never had a deer jump the string on me either.The self bow is the silent assassin.
I never shoot at a deer looking right at me in the stand with a bow.Even if they are so close I can see their eyes blinking.Using a gun is a different thing.

[Don W]

I would love to have a bow that would shoot a 600 gr arrow at 170fps! I make my own arrows, and most are in the 600 gr range. I'm working on getting them to go faster, but for now I'll need to settle on 140-150 fps.

[BowEd]

That'll still do the job easily Don.Especially under 20 yards.Good luck with your hunting.
If you've ever seen these hunting shows where the hunter will say over his dead deer that he could'nt be happier after shooting it with a gun at 150 yards.He does'nt know what he's talking about and missing out on what it feels like killing deer with a self bow and self arrow.

[Tommy D]

I would love to have a bow that would shoot a 600 gr arrow at 170fps! I make my own arrows, and most are in the 600 gr range. I'm working on getting them to go faster, but for now I'll need to settle on 140-150 fps.

For what it’s worth Ashby puts 650 grains as a sort of “magic number” above which you get a jump in penetration ... I don’t know how exact this figure is or why... he also puts much importance on an arrow being 19% FOC and above. For me, I have struggled to get this FOC at any weight below about 650 grains with bamboo arrows... they seem to go hand in hand.

With more FOC, in theory, you need less fletching to get good broadhead flight - and Ashby himself doesn’t use an offset fletch ... so again - in theory - you trade some speed for a quieter arrow...

On my lighter bows (45lbs) they do feel a little slow in flight for my liking, but if one goes on the principle that you aren’t going to shoot anything over 20 yards - then for me at least, at that distance, they are pretty much point on for me (I shoot 3 under) ... so I wouldn’t feel handicapped by an arrow of this weight at all...

In addition, I also think people totally over estimate the idea that a slightly faster arrow is going to compensate for an animal jumping the string or moving as you take the shot. I would trade penetration over arrow speed any day.

Ashby’s reports are the real deal - and he’s done the hard work - so I certainly pay a lot of attention to them.

One final point he makes - which I think is very true is that “mass/weight belongs to the arrow - you can’t take it away - but the instant your arrow hits something it’s speed drops rapidly” ... so basically in your momentum equation - mass x velocity - you are better off making up the momentum with mass over velocity, because you can’t rob the arrow of the mass component as soon as it hits something...

You may enjoy this article by Ashby on hunting in Papua New Guinea where I believe some of the arrows Ashby handled were up to 4000 grains!

 https://journalofmountainhunting.com/primitive-bowhunting-lessons-papua-new-guineas-png-bows-and-arrows/

[Don W]

I am not close to caught up on the reading, but the links are appreciated and I'll definitely be going through them all. It may not be until winter sets in, and maybe even longer, it all looks pretty in-depth.

[BowEd]

Correct Tommy D about FOC for penetration.
Carbide arrows are easy to get balanced FOC 6" from the tip.With wooden full length tapered dogwoods maybe 9 to 10 inches balance from the tip.Which puts them in the high teens maybe low 20's percentage wise FOC.Flying clean and true quickly from the bow.A real bone busting shaft IMO.

[Tommy D]

I am not close to caught up on the reading, but the links are appreciated and I'll definitely be going through them all. It may not be until winter sets in, and maybe even longer, it all looks pretty in-depth.

Here is a summary by Ashby (with real world numbers) of the relationship between mass and velocity - for one of his bows.

Also, some examples of how when you use “momentum” as the measure of an arrow’s lethality (over Kinetic energy - as is the norm in many circles), you can better understand how a bow and arrow can be just as lethal as a firearm.





The whole article is here https://journalofmountainhunting.com/part-iv-the-physics-of-arrow-penetration-by-dr-ed-ashby/