Double Creek

What else do we have to do in the off season?

Seriously, that is is very good point and one that need to be remembered.

TFOX

jca,I do agree with most of your post but not all heavy arrows retain more speed or ke than the lighter counterpart.An ACC and a Kinetic II will retain more of it's original velocity and ke downrange than an aluminum arrow.Also a heavy arrow will generally require more guidance at the backend of an arrow to get a heavy arrow to fly accurate at longer distances than it will a lighter arrow and therefore,more fletching equals more drag.ACC's are some of the best penetrating shafts on the market but are substantially lighter so the arrow make up plays a huge part in the equation and isn't just weight,verses speed, verses ke, verses ke.



By definition,ke will play a huge role in penetration but so does momentum.Ke is part of what helps keep an arrow straight in flight and that is a big part of penetration,more ke equalls more inherant ability to remain traveling straight and PARALLEL on impact.Momentum gives you more bone crushing force to basically just keep going regardless of what gets in it's way and speed gives you friction fighting ability so basically just get a well balanced arrow that is well tuned and go hunt and don't overthink this penetration stuff.Shot placement will take care of it.

Buckfevr

I think that you may have just figured out the optimal point weight for the spine of that arrow out of your setup rather than the optimal weight arrow for your setup.

Mike from Texas

What makes you say that?

Buckfevr

I think that what you've mostly found is the point weight at which the spine of that particular acc is weakened so that it doesn't retain as much energy. Seems like the 100 grain head is as heavy as you can go for that arrow. And that's good lots of broadhead offerings in 100 grains. But I do wonder for instance if you went to a heavier arrow like a big game 100+ if you wouldn't find that the KE would be retained at a heavier arrow weight given the heavier spine. Or maybe a 3-71 with a 125 point head.

I think the only issue would be is how critical is the bow is at 287. But that is a nice weight to be getting that kind of speed.

Mike from Texas

I'm still not understanding where you are coming from about the point weight in relation to spine and what effect is has on ke/momentum. As I understand it, KE and to a point, momentum are directly related to speed and arrow weight. I just plugged in different arrow weight for my setup and it automatically caluculates the speed based off the IBO speed I plugged in from my bow. I have chrono'd this bow at IBO specs and it will shoot 326 fps with a tied on nock and bare string. I basically plug that in, deduct for each grain over IBO minimum plus all string accessories and come up with a speed and KE figure. Regardless of what arrow I am using for the weight calculations, I don't see how your scenario has any bearing on the ke or momntum. Simply put, it reaches a point to where the lines of speed and KE cross at some point and then both figures begin to go down. On my bow, that optimal combination seems to be 440-444 grains. At 445 grains and above, the KE as well as the speed begins to drop off.


BTW, you were wondering how my bow shoots at 287 fps, here's a pic of a combination 20 and 30 yard group I shot while shooting one pin to get the idea of how the trajectory is on this bow. This was a 390 grain arrow at 308 fps.

walks with a gimp

Looks like to me that your speed, K.E and accuracy is good enough for anything from sparrows to grizz Try some of my favorite XX78 2315's for accuracy and quiet hunting, should weigh around 555 grains in 30 inches and speed will still be around 265 fps.

Mike from Texas

Nah, these ACCs have served me well over the years. I think I'll stick with them and keep the extra speed.

Buckfevr

Damn nice group!!! You shooting one pin for hunting?

PABowhntr

I stopped after reading this one line......

Personally, I am surprised that your maximum KE numbers came out with a 442 grain arrow. In most of the cases I have run through, hypothetically, the arrow weight was significantly higher. However, if you are also factoring in trajectory then I can see where an arrow weighing between 400-450 grains would be the "best of both worlds" for most setups today.