I shoot 1,500 to 2,000 arrows per year which means I'm out target shooting easily 3 to 4 times weekly. I still find "Canting" to be the single most critical factor adversely affecting shooting consistency at longer distances from 60 to 120 yards. It also has an enormous effect on short yardage shooting at 20 - 40 yards, but this is in smaller amounts. Please read the article and then you'll understand what I mean.
“Canting” a Crossbow – What is it and how to correct it?
How many of you know or understand what "Canting" your crossbow means or how to avoid this problem?
The purpose of this thread is to provide a basic understanding of this problem and offer some simple, effective solutions.
Precision rifle shooters know how to avoid accuracy problems caused by canting (or tilting sideways) their weapon. Normally this issue becomes a "hunting accuracy" problem only out at several hundred yards. But it’s important to realize that the "problem distance" is related to the number of inches of bullet drop, not so much the distance itself. And even a fast 400+ feet per second crossbow has about 100 inches of drop at 100 yards. About the same as a flat shooting rifle at say, 700 hundred yards.
The following example is slightly over-simplified but the numbers are pretty close to actual, so you should get the idea.
Using a 400 fps. crossbow, if you sight in your crossbow at 20 or 30 yards, there is a drop at 100 yards of approximately 100 inches when using an arrow weighing approximately 410 grains. Picture this. Place an 8 foot 2” X 4” at a distance of 20 or 30 yards and sight in so that when you aim at the bottom of it, you hit the bottom of it.
Now move the almost-100-inch 2” X 4” out to 100 yards. If you hold your crossbow perfectly level and aim at the top of the 2” X 4”, you’ll hit the bottom of the 2” X 4” due to the arrow drop that we just outlined.
Next, tilt the 2”X 4” slightly to one side, say 5 degrees, which is the same as one minute on a clock face. Not very much at all, is it?
Now take a string and attach it to the top of the 2” X 4” and let it fall to the ground. You'll see that it’s about 12” to one side of the bottom of the 2” X 4”. This means that when you aim at the top, you will hit about 12” off to the side of your aim point.
To emphasize, this means your arrow will impact 12” off to the side and your deer who is now badly wounded, or missed if you are lucky.
Interesting aside -- if you are not hunting, but simply shooting groups at 100 yards -- and if you don't control your cant, even a slight cant off a level bench can throw your groups off by several inches or more. Most people assume it was wind, or they flinched at the last moment, but it wasn't. One degree of cant at 100 yards is twelve inches of horizontal error. By the way, in all these crossbow cases the vertical error is negligible.
So, what do we do to correct this problem and eliminate it from affecting our shooting performance? It's easy to keep level if you’re shooting from a perfectly level bench, or when shooting prone from level ground.
But what about shooting sitting on a hillside or from a tree stand, while in the heat of the moment? Do you really think you can tell when you’re crossbow is tilted even 3 – 5 degrees at any given distance?
If you adjust your windage setting on your scope to compensate for the problem, and then move back to a longer distance such as 50 yards, you will again be off center, due to the fact this problem continues to magnify as you increase your distance as was explained using the string and 2” x 4” concept. The more the degree of Tilt / Cant and the longer the distance the more off target one would be.
To solve this problem we use a bubble level mounted to the top of our scope rings. Hopefully, if you’ve leveled and squared your crossbow properly, you already know that when your crossbows rail is sitting perfectly level and then you use a torpedo level across your limbs or a “Line Level” on your crossbows string, you already know these two parts are both in agreement with one another and are sitting perfectly level. Next, simply attach a scope level like the one pictured below to your existing rear scope ring and gradually tighten it until it is in the exact same level position as the other two levels that I just mentioned. Also insure that your scopes horizontal crosshair is also perfectly level. Once these steps have been completed, you should always be able to take a quick glance at you’re the level above your scope to insure that your crossbow is not canted during a shot. This will greatly improve your shots by removing all left / right deviations other than those caused by wind. This is one of the single most important tuning aids that a crossbow shooter can add to his equipment and it’s one of the most important tools that all long range shooters rely on for consistent accuracy as the shot distance increases.
The following level that’s being displayed below can be bought for about $10.00 on ebay and usually takes about 10 minutes to install on most scopes. They are scope ring size specific, so if your scope has a 30mm tube, then you must order the one for that size rings. If your scope uses a 1” ring, then order the correct size for your scope, since they are not universal.
I hope this helps some of you understand the issue of Canting and why using a level is so critical to accurate shooting success.
In case anybody wants to get one or take a closer look at them, here's the item number: 251014571864
Regards,
Xbow755
