Author Topic: broad heads too wide?? (Read 677 times)

willis5 · « **on:** December 17, 2003, 02:31:32 AM »

Some of the expandable broadheads are really wide 2+inches. What is the average distance between a deers ribs?

I know the arrows will often go through or even glance off a rib and still penetrate, but what if you hit TWO ribs on penetration because of the oversized broad head width?

Is this going to slow the arrow down too much?

Myk · « **Reply #1 on:** December 17, 2003, 03:45:27 AM »

Breaking ribs shouldn't be a problem for any hunting weight bow.

The problem some people may have with any mechanicals is shooting too light of draw weight, too light of arrows or both. Take away energy and momentum needed to open the blades then take away energy and momentum needed to cut the larger diameter and it can spell disaster.

Vortex broadheads may cause their own problem because their blades are almost perpendicular to the arrow. This causes a pushing action rather than a slicing one.

I started shooting a 1 3/4" mechanical this year. My personal thoughts are you should at least have 50 ft/lbs of kinetic energy (perferably more) and at least a 400gr arrow. The mistake many make is only looking at the kinetic energy side of things. Since KE gets velocity squared the lighter arrow you shoot the more KE you get (to a point). Momentum doesn't get anything squared and I think the average grain loss to fps gain causes you to end up losing momentum when going lighter to gain speed/KE.
Then they wonder why their feather weight arrow used up all its KE opening the head.

So to answer your question, "Is this going to slow the arrow down too much?". It depends on the set up.

willis5 · « **Reply #2 on:** December 17, 2003, 06:59:11 AM »

That is a great point. I don't even consider arrows that are super light, so I never thought of it.

that "Pushing" action is what i was concerned about, but I guess if you have the weight (grains and pounds) it isn't going to matter. Thanks, Myk.

Myk · « **Reply #3 on:** December 17, 2003, 07:46:22 AM »

I have a friend who shoots the big Vortex heads. He seems to do OK with them but he is rather large and a farm boy who grew up bailing hay and working with draft horses so I imagine he's pulling 70lbs.

The ones I shoot are Jak-Hammers, the blades lay back pretty good. They also opened early enough that there was cut hair on the entry.

Just to give you an idea.
With about 460gr total arrow weight and pulling 63lbs I barely had an incomplete passthrough on a 30yd shot. One of the blades clipped the spine on the way through but the blades did break ribs on both sides and the point did poke through the off-side skin.

So from that experience I consider that a minimum draw and arrow weight for that bow. I hadn't chronographed that set up but after I added 3 more pounds I was getting about 230fps. I'd guess I was getting 220fps before.

My new bow is shooting 555gr arrows at 230fps with 63lbs of draw so I think this new bow will not have any problems. I'll probably go with my 460gr arrows to get the flatter trajectory, but if I have to get new arrows I doubt if I'll go much lighter.

willis5 · « **Reply #4 on:** December 18, 2003, 02:04:38 AM »

are your arrow weights total or just arrow? i am guessing total w/broadhead.

Myk · « **Reply #5 on:** December 18, 2003, 04:17:43 AM »

Total. 100gr broadheads, which is another reason I want to go to the lighter arrows, they put the center of balance too close to the center with the heavier ones.

willis5 · « **Reply #6 on:** December 18, 2003, 06:03:17 AM »

I understand. You would still have enough momentum and k.e. while going a little lighter

Bowhunter57 · « **Reply #7 on:** December 21, 2003, 09:58:55 AM »

willis5,
Shoot your bow through a chronograph with a finished arrow. (Finished arrow = as it flys out of the bow for hunting purposes.)

Here the Kinetic Energy formula:
F.P.S. x F.P.S. x Total Arrow Weight = K. E.
450,240

Hope this helps you find the K.E. that you need for your set up.

Good hunting, Bowhunter57