Friday, October 14, 2022

Sighting in a new cross-bow

I went out to the hunting-lease with Shotgun today.

My goal was to sight-in my newish crossbow.

Shotgun's goal was to verify the zero on his.

I was not successful. He was.

Darned if I was not capable of pulling the string by hand. I just could not get the cam-wheel over-the-hump. Recognizing that I am not getting any younger I bought a "cocking rope" on the way home.

Shotgun graciously allowed me to take his target so I could do my sighting-in at home.

For those who are not familiar with the trajectory of projectiles, the path is roughly parabolic like a clothesline but upside-down so it arches with open-side down. The parabola is lopsided because the projectile slows as it encounters air resistance and the ending part of the parabola arches more sharply downward.

The projectile typically leaves the weapon below the line-of-sight, passes through it on an upward angle, flattens out somewhere above the line-of-sight somewhere mid-range and then drops downward and encounters it again. 

There are two schools of sighting-in a weapon. I subscribe to the simple way. I think multiple cross-hairs are invitations to making errors when gripped by buck-fever. I want a single cross-hair and I want the mid-range elevation to be between 2" and 3" above the line-of-sight. Then I can put the cross-hairs on the center of the target's chest confident that I will get a hit if it is within range.


Shotgun subscribes to the church-of-multiple-strata Reticulatum Complicatum Gollydangum. My beef with multiple horizontal hash-marks is that it is counterintuitive to use the higher cross-hair for mid-range targets and the lower cross-hairs for distant targets. The mind does funny things under stress. "I need to hold higher for distant targets..." goes the thinking "...so I need to use the higher cross-hairs." Wrong!

But Shotgun is a full-grown man. He will do what he does. Life gets very complicated when you try to squeeze 10 more yards out of a 40 yard weapon. Worth it if the target can shoot back. Otherwise, I am not so sure.

Based on the trajectory of his cross-bow, if my produces a similar trajectory then my "max range" will be in the neighborhood of 35-to-40 yards using a simple scope and a 3" maximum mid-range excursion from the line-of-sight.

Any comments will be appreciated.

7 comments:

  1. I agree with you Joe. The simpler the better. Know your range and the size of the target and the trajectory of your arrow/bullet and you can make a good accurate shot with a simple crosshair. Or an iron sight. ---ken

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  2. It appears I can't resist a tangent. There has been a passing idea that having a modern spurting thingy could theoretically be a less than totally stupid idea. Your talk about cross hairs reminded me of an item for the above mentioned MST. The item in question is a front post with a brass cross hair embedded so you can see through it to your point of aim.To me this seemed like genius. When I mentioned it to a more experienced person,the comment was naw don't need it.(if you need a better description its available at a place with a name like the smaller Chicago airport)

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  3. Here is an excellent video on AR-15 zero.

    https://www.youtube.com/watch?v=DFbpjNh4DBA

    I prefer the 50/200 yard zero. Simple.

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  4. I can appreciate the common sense approach to take a shot only if you are sure of it . I only wish more hunters had that discretion. This homestead is surrounded by a 2400 acre gated , guarded community on the east , an 800 acre girl scout camp on the south , and a 900 acre boy scout camp on the west side with the north being open farm land for a couple miles . The result is hordes of deer wandering this 40 acre wilderness tract looking for goodies . We find at least three and sometimes more wounded , suffering , or dead deer every season where someone took a poor shot or was just too stupid to track there kill . If it's fresh enough I take it for dog food but most times it has rotted and goes to waste except the Yotes of course . That takes me back to your earlier post on that Catholic Saint and his hunting standards . Good stuff ! I love it when doctrine hits you where you live .

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  5. The issue is time of flight and the game jumping the string. At the sound of the bow or crossbow, they will hunch and then leap forward to run. It is almost certain that by the time the arrow arrives, it will not hit where you are aiming. The longer the range, the more time the animal has to move, and the greater the chance of a blown shot and wounded game. 40 yards is a very reasonable working max range, Joe. Going much beyond that is just asking for trouble.

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  6. Reticulatum Complicatum Gollydangum. This made the whole article for me! When I first started deer hunting I was using a 20ga shotgun with a rifled barrel. While it was theoretically capable of making a 100yd shot I would never take one that long as I didn't trust my marksmanship under pressure at that distance with that gun. I took several deer with that gun, and they were all 50yd shots or less. As the old sage Harry Callahan used to say, "A man's got to know his limitations."

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