zac76156

I read in some bowhunting mag a while back that the minimum recommended kinetic energy for shooting mechanicals was like 55 ft/lbs. I'm just wondering what you guys thought. Those of you shooting mechanicals, how much KE are you putting out?? What would you all consider the minimum to be??

Paul L Mohr

It depends on what head. Some seem to work pretty well with lower poundages. The spit fires need a fair amount it seems. And any thing with a large diameter would need more.

I shoot Nail Drivers that are a small two blade. They seem to work pretty well on my light set up. However they don't really offer any advantage over a small fixed blade. Other than slighty better flight.

Check out 5-shots web page, or maybe he will comment on this post.

Paul

Jeff K

Well all depends on the B-head. Some like the Spitfires require 55 lbs +, according to NAP, but I would want more like 60 lbs + for them. I shoot 100gr Rocky Mtn. Snypers, perhaps the best mechanicals I have ever shot. My set up is, total arrow weight w/ B-head is 388.8gr (That is a 29" Gold Tip XT=8.2gpi), I shoot a Mathews LX at 28" Draw at 65lbs shooting at 268fps, my calculations work out to be 62.02 KE. I will be switching arrows soon, to the Gold Tip Pro Hunter 75/95 which will add a little more arrow weight. That calculation for the same set up on the bow, just different arrows,would put me at 64.8 KE.

The equation is weight x velocity x velocity divided by 450,240

ranchand99

Quote:

Recommended standards: It has been offered by some experts that 45 ft-lb of arrow energy is a good minimum for whitetail deer, while 55 ft-lb is a proper minimum for elk and caribou. It has been further suggested by several in the broadhead business that an extra 10 ft-lb should be added to each of these minimums when mechanical broadheads are used. These, of course, are only rough guidelines. Many animals have been taken through the years, and will continue to be, with well-placed arrows carrying much less energy.

PatriotDually

I am shooting 72#'s with 29" draw and 570 grainarrows, so i am producing about 120lbs of KE. But yea i hear you need about 55lbs to shoot the Nap spitfires.

Jeff K

Actually that is 128 Lbs of KE, but I mean come on I don't think you are flinging a 570gr arrow at 318fps that is a bit ridiculous, a IBO rating for your bow is 326-334, remeber IBO system uses a 350gr arrow at 30" draw and 70lbs pull. Ok your arrow is 220gr more than that and 30gr more than the AMO rating which is 540gr at 30" and 60lbs pull. Mathematically I don't think that 2 lbs pull difference from the IBO testing is going to catapault you to 318fps, not to mention you lose speed when you decrease your draw length. If I had to guess a speed, it would be about 265fps-290fps, no more because of your outstanding arrow weight, which would put you at 99 lbs of KE. You lose speed at 29" draw, you lose speed because of the arrow weight, and you gain a little back at 72lbs pull.

Dubbya

Yeah, I have to agree with Jeff, I was wondering that myself. I shoot a 72# razortec at 29" draw with a 420 grain arrow at 279-280fps. This means I'm producing just under 73# of KE. I shot a hog (the one in my avatar) at 20 yards with a cut on contact mech head and it blew a huge hole out the back. I know a guy that shoot 61 foot pounds of KE and has never had any problems with his mech heads. Good Luck.

marmax

Trapper_Hunter

I only get around 55 kE and got a passthrough with NAP shockwaves.

ijimmy

Like Paul said , depends on the head you use . Buckblasters , and hammerheads are going to require some punch , 70-75lbs+ of ke for passthrus on good sized deer , while Id have no problems shooting vortex pros , a 2 blade 1 1/2 inch cut out of a 45lb+ bow . Which ever head you use make sure they are deadly sharp , many come out of the package not sharp enough , and that the blades swing freely .