Broadheads were originally designed for war usage. Their purpose was to deliver a wide cutting edge so as to kill as quickly as possible by cleanly cutting major blood vessels in the enemies they struck. They usually have two to four sharp blades that cause massive bleeding in the victim.
Today the main purpose of the broadhead is for hunting with archery equipment in specialized archery seasons.
There are two main types of broadheads used by hunters: The fixed-blade and the mechanical blade.
While the fixed-blade broadhead keeps its blades rigid and unmovable on the broadhead at all times, the mechanical broadhead deploys its blades upon contact with the target.
So in light of those facts here are the facts as they exist on arrow broadheads, this should help you in your quest for the right broadhead choice for your imparticular crossbow arrow and or bolt.
Best weight of broadhead for kinetic energy retention.
Industry experts recommend 100 grain broadheads for carbon and lightweight aluminum arrows, and 125 grain broadheads for heavy aluminum arrows. The reason for this can be simply explained by the angle of the arrows flight as it impacts its target allowing the arrow to push squarely on the broadhead to force it through whatever it encounters. (Front Of Center Technology or F.O.C.)
Best diameter of broadhead for kinetic energy retention.
As a general rule, for crossbows of lower speeds and lighter arrow weight 1 1/8" and smaller diameter broadheads will give you far better penetration because of less resistance of the smaller diameter of broadhead which makes good use of the lesser amount of kinetic energy your crossbow has to offer.
Broadhead diameter misconception.
Broadhead diameter is somewhat mis-leading when it comes to broadheads and this fact on broadheads is considered very little when in fact it is quite important.
Broadhead surface cutting area, is more to the point as to why you choose a broadhead.
First illustration, accurate, 1 1/2" diameter 2 blade mechanical broadhead, surface cutting area 1 1/2".
Second illustration, very accurate, 1" diameter 3 blade fixed-blade broadhead, surface cutting area 1 1/2".
In the illustrations above the mechanical blade broadhead appears to be way bigger than the fixed blade broadhead when in fact they both have the exact same surface cutting area.
Mechanical broadheads.55 Foot Pounds for: Medium Game such as Deer and Antelope.65 Foot Pounds for: Large Game such as Elk, Black Bear and Wild Boar.
Below you will find a list of recommended crossbow arrow kinetic energies needed for various game animals using a good mechanical broadhead up to 2 inches in diameter.
The advantage of using mechanical broadheads is; they fly very close to field points. The critical issue to keep in mind with mechanical heads is that the blades have no support for the trailing edge of the blades. Crossbow-hunters should really limit the size of their broadheads to a maximum cutting diameter of 1-1/2 inch when going after elk or other big-bodied animals like moose or bear where penetration is critical.
Fixed blade broadheads.20 - 25 Foot Pounds for: Small Game25 - 41 Foot Pounds for: Medium Game such as, Deer and Antelope.42 - 65 Foot Pounds for: Large Game such as Elk, Black Bear and Wild Boar.65 - 70 Foot Pounds for: Toughest Game such as Cape Buffalo and Grizzly.
Below you will find a list of recommended crossbow arrow kinetic energies needed for various game animals using a good fixed blade broadhead.
The two types of fixed blade broadhead configurations.
1. Replaceable blade type, chisel tipped broadhead: - The blades are removable for sharpening or replacement. Broadhead's that use a chisel tip have to punch or rip through an animal's hide before reaching the broadhead's blade cutting surface. This will use some of the arrow's kinetic energy thus impeding penetration. This style of tip is durable and will push through heavy bone.
2. Cut on contact, one piece broadhead: - Full blade broadheads have cutting edges that extend from the tip of the point back to the rear portion of the blade. Cut on contact, one piece broadheads slice through hide which requires very little kinetic energy, therefore penetration is better than the chisel tipped, these are a good choice for very low powered crossbows.
Best diameter of broadhead for accuracy.
The design of some fixed blade broadheads is not conducive to accurate shooting as they may have extremely large surface area, blade shape, or other design characteristics that, when used on an arrow shaft of 22" or less, will not fly well.
The shorter the arrow you are shooting, the more difficult it is to get extremely tight groups with some broadheads. If the heads have too much surface area or a very large cutting diameter, they will plane easily from catching air in flight.
Short 1 1/8" diameter or less broadheads are for the most part very accurate on any arrow.
How to gain accuracy from a broadhead.
Simply put, if your broadhead is steering your arrow in the wrong direction and is not accurate, add bigger or more fletching to your arrow with a right or left helical twist as this will somewhat cancel out the broadhead steering the arrow.
Heavy boned animals such as elk or bear: The chisel tip fixed blade broadhead works best as it has the ability to penetrate heavy bone without destruction to the broadhead itself.
Thin skin animals such as deer & antelope:
Hunting from a ground blind or stalking, a small diameter one piece broadhead offers the hunter accuracy with good penetration on the animal, leaving a good blood trail to follow.
Hunting from a treestand, because of the extreme angle of this hunting position a large diameter cut broadhead is recommended as it is easy to miss most of the vitals in the animal.
Broadhead diameter test and blood trails.
2009 archery deer seasons we had used 3 blade, chisel tipped, fixed-blade 7/8" diameter, (1 5/16" surface cutting area) broadheads from ground blinds to see if the extreme accuracy gained from using a small diameter broadhead on broadside shots catching both lungs of the deer, left better blood-trails than a treestand shot where only one lung may be hit with an expandable broadhead.
This test was very visual in its outcome, the accuracy gained by using small diameter broadheads is worth noting; (1 1/2" at 50 yards).
The blood-trails were much heavier with the accurate ground blind horizontal double lung shot as opposed to the near vertical one lung shot from a treestand using an expandable broadhead.