October 30, 2015
By Jon E. Silks
Our Practical Bowhunting Test Series is designed to be just that — practical. This fifth installment focuses on how shooting into foam targets impacts the sharpness of your broadhead blades.
Many bowhunters I know will not hunt with a broadhead unless it is fresh out of the package. These archers would not dream of reusing a head shot into their practice target, and some of them would even criticize fellow bowhunters who did. After all, we have had this mindset drilled into our heads for a very long time. The question is, where did that thinking come from, and does it still hold merit?
Years ago, when hunting bows were considerably slower than they are today, bowhunters used hay bales, homemade cardboard mats, sand pits, leaves laying in the yard or whatever else they could find to verify the accuracy of their setups. There were a couple issues with those targets. First, some of the materials, such as the hay bales and cardboard, wouldn't always stop the arrow.
So, you were hitting the dirt or other objects behind them. Second, you never knew what might be lurking inside the target. We found gravel in hay bales, rocks in sand pits and of course if you passed through and hit the ground you could encounter just about anything. It's not hard to imagine broadheads being dulled or damaged during such practice sessions.
These days, however, virtually all broadhead practice is done with some type of manufactured foam target. These targets are available in a variety of shapes, sizes and price points, but the bottom line is that modern broadhead targets are made with materials that ensure a clean and consistent backstop for our arrows.
Still, no ethical bowhunter would head afield with a broadhead shot into any material unless he or she was extremely confident that head would still perform just as well — or very close to it — as a brand new one right out of the package. That is where this month's test comes in; we have produced data that sheds light on the impact foam targets have on blade sharpness.
We started with the hard-hitting Hoyt Carbon Spyder Turbo, which was tuned perfectly by Len Marsh at Macrotech Archery in Baltimore, Md., to shoot 28-inch Easton Full Metal Jacket arrows that weighed 465 grains, including 100-grain fieldpoints. The draw length was set to 28 inches and the draw weight to 68 pounds. We used an Archer Xtreme Titanium Recon arrow rest and a standard string nocking loop. This setup produced an arrow speed of 290 fps, which resulted in 86.86 foot-pounds of kinetic energy.
All test shots were fired by hand at a distance of 10 yards and all hit a "fresh" spot on the targets. Three targets representing three different manufacturing processes were used.
They included a Rinehart mule deer target featuring the company's signature, self-healing, solid foam, a GlenDel Full Rut Buck featuring a layered-foam core with a thin outer layer of solid foam and a new Delta ShotBlocker Ultimate target made of heat-welded layered foam. Blades from Rexpid, New Archery Products (NAP) and Innerloc broadheads were used.
Prior to testing, we sent 14 brand new, fresh-out-of-the package blades to the Cutlery & Allied Trades Research Association in Sheffield, England for initial sharpness measurements. These readings served as our baseline when comparing the sharpness of the same blades after testing. CATRA is the same vendor we use for other tests and is one of the few sources around the globe to provide accurate, standardized sharpness testing.
To gauge how much sharpness is lost while shooting into foam, we tested in increments of one shot, seven shots, 14 shots and 30 shots. We picked those numbers with some purpose. A single shot is theoretically all you would need to verify if your bow is still sighted in and your arrow and head are flying correctly.
Seven shots would be more in line with a bow that needed a slight adjustment or two, and 14 shots is approximately how many you might need to get things back on track if things are really out of whack. We also decided to test one blade after 30 shots as an example of what you might experience after repeated practice sessions with the same broadhead.
Once our testing was complete, we sent the same blades back to CATRA to be re-tested for final sharpness results.
Before discussing the results, we need some context to make sense of the numbers/values assigned by CATRA.
First, let's outline the procedure used. Each sample blade was tested using CATRA's REST (Razor Edge Sharpness Tester) machine that pushes the blade into a standard, 3mm rubber test media at 0.1mm per second and measures the peak force required to cut the media, in Newtons.
The lower the number, the less force required to cut the test media and the sharper the blade. So, when looking at the results chart, the additional force required to cut after the test shots were fired is the amount of dulling that occurred.
To help put the results in context, consider the following:
€¢ Standard shaving razor blade: .3N
€¢ Typical hunting knife: 1.5-2.0N
€¢ Out-of-the-package sharpness range of 13 brand-name broadheads in our recent fixed-blade broadhead test: 0.86-2.69N.
What the Numbers Mean
So, what can we learn from the results? Well, the most obvious thing we learned is that shooting into foam does indeed dull broadhead blades. However, the amount of dulling that occurs is very minimal. In fact, I think it is safe to say the degree to which the blades are dulled — even after repeated shots — is significantly less than many bowhunters would expect.
It is also important to note that even after repeated shots, the blades in our test were still quite sharp. Consider that none of the post-test sharpness values was above 1.94N. And if you take out the 30-shot test, that number shrinks to 1.51N.
The post-test sharpness of all the blades in our test compares very favorably to the brand new, out-of-the-package sharpness of the 13 heads in our recent fixed-blade broadhead test — major, brand-name products trusted by thousands upon thousands of bowhunters — that ranged from 0.86-2.69N. And considering that a typical hunting knife ranges from 1.5-2.0N, all the blades in our test were still knife sharp even after multiple shots.
Second, while many bowhunters may not consider shooting their primary broadhead into a foam target regardless of the data, there are indeed situations and reasons to warrant relying on the information here and sending a verification arrow or two down range. One situation that qualifies is forgetfulness; if you have a memory like mine, this is a real possibility.
Let's say you reach your hunting destination, far from the nearest bow shop, and realize you forgot your practice heads but remembered your portable foam target. Based on these results, I would not hesitate to take a single shot with one of my hunting broadheads to confirm accuracy. If it still really bothers you, then just move the verification arrow to last place in your quiver.
Another reason to take some practice shots with your hunting heads — one I can personally relate to — is general cash flow. When I first got started bowhunting, I had so little money I used a matchstick taped to my riser for a sight pin! Many broadheads are relatively expensive, and dropping $30 or $40 for an extra pack of "practice heads" may not be the best option when, based on our data, you can confidently shoot a couple of your hunting heads for setup verification and still expect killer performance.
You know, the worst scenario is a bowhunter deciding not to shoot that practice shot based on bad information and then making a bad shot in the field because their rig was off. With the data we produced in this test, I would much rather they take that practice shot or two and have the confidence in their equipment.
If you have the money to spend on purchasing additional broadheads specifically for practice purposes, then by all means stock up. However, if you find yourself in the situations described above, then based on our data you should have the confidence to fire a few practice shots and still go out and chase that trophy of a lifetime.