why that broadhead

[nchunterkw]

Momentum is mass times velocity
P=mv

KE is one half the mass times the square of the velocity
KE=(MVV)/2

That is a huge difference especially when talking about velocity.

In momentum mass and velocity each contribute linearly. It is easy to see that a 400gr arrow going 300fps and a 300gr arrow going 400fps have the same momentum. And if resistance forces increase with the square of the velocity that the faster arrow will have to overcome much more force inside the animal. But the trouble is it has less mass to do that with.

But I agree with you too. 400ish grains and a coc head out of these crossbows will blow through about any whitetail. Since I agree with Ed ashby I tend to up that some to hopefully still get the pass through when the shot is not perfect. And for pigs and bison.

Here is a link to one of ashbys articles if you have never read his stuff. It makes sense to me.

http://www.alaskabowhunting.com/Ashby-O ... n-W19.aspx

[Kegbelly]

Agreed, basic physics says the heavier projectile will penetrate deeper even though it's slower because it has more mass. An object in motion, etc...KInd of like a 16 lb bowling ball vs a 10 lb ball, the heavier ball is more likely to carry thru the pins better because it takes more opposing force to stop it even though the lighter ball may be traveling faster. But at some point diminishing returns will come into play on both ends of the speed vs weight argument. So my point is if you're already shooting clean thru an animal with say 375 grains, it's just wasting energy on whatever is behind the target with a heavier arrow. For extremely big, heavy game or dangerous game, you need the heavier arrow for the deeper penetration to ensure your arrow reaches the vitals, but for the average whitetail it's sort of a moot point IMO. Lots of guys prefer heavier arrows because they feel smoother and quieter when shooting them, and that's a valid reason in itself. For me I've tried to find a happy medium between velocity and weight and still achieve the desired results--accuracy and complete pass throughs-- and 370-380 grains seems to be a perfect combination. Good discussion!

[jparchery]

I use a Swhacker broadhead 125 grain, shot 2 deer with them last year and no problems at all, i love them

[nchunterkw]

Yes! nice discussion bringing out different points of view. And your point about a heavier arrow being smoother is a good one. I also think the crossbow is a little more efficient with a heavier arrow - transferring more energy to the arrow - hence the quieter shot with less vibration. That being the case, it should translate into less after shot stress on the bow. Not that I am worried about long term reliability with these bows. I also hunt a lot from the ground and have found a heavy arrow travelling with some arc, even at 20 yds, results in more found arrows. Shot a pig at 20 yds , broadside, last year with a 525 gr arrow from a ground blind, and the exit wound was actually a little bit lower than the entrance wound and the arrow was sticking in the ground about 10 yds or so behind where it was standing. I really like finding my arrow, it's like finding a $20 bill lying on the ground.

So this started with my reply to VixenMaster about his results with the Swhacker. In that case (lighter bow, wide mechanical) I think a heavy arrow is a must. I think we underestimate the energy required to open those large blades and push them through a deer. What do you think?

[paulaboutform]

Agreed, basic physics says the heavier projectile will penetrate deeper even though it's slower because it has more mass. An object in motion, etc...KInd of like a 16 lb bowling ball vs a 10 lb ball, the heavier ball is more likely to carry thru the pins better because it takes more opposing force to stop it even though the lighter ball may be traveling faster. But at some point diminishing returns will come into play on both ends of the speed vs weight argument. So my point is if you're already shooting clean thru an animal with say 375 grains, it's just wasting energy on whatever is behind the target with a heavier arrow. For extremely big, heavy game or dangerous game, you need the heavier arrow for the deeper penetration to ensure your arrow reaches the vitals, but for the average whitetail it's sort of a moot point IMO. Lots of guys prefer heavier arrows because they feel smoother and quieter when shooting them, and that's a valid reason in itself. For me I've tried to find a happy medium between velocity and weight and still achieve the desired results--accuracy and complete pass throughs-- and 370-380 grains seems to be a perfect combination. Good discussion!

Good discussion indeed. I agree on both ends saying there is a balance point or sweet spot. For 3D my arrows weigh 5gr per pound of draw (315gr) and for hunting my arrows weigh about 6.25gr per pound of draw (430gr). That equals about 337fps vs 270fps. Regardless, with the more power/force you have the more you can get away with in terms of equipment used. That's all I was getting at.

[Kegbelly]

Yeah, finding that sweet spot that makes you happy is part of the fun!

Good point about heavier arrows dropping closer to your game... I hunt off the ground too some, and shooting level you can just about kiss your arrow goodbye on a good pass through shot, it's out there in the woods somewhere