Shooting question

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Ponsoldt2

Member
Jan 13, 2021
24
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Florida, United States
I mounted two golf balls on the other side of a canal. The distance is 78 yards. I have hit them but not consistently probably more luck then anything else.

Facts:: I am shooting an unregulated marauder. I can site it in for anything from 10-25 yards. I have no idea of the speed it shoots as the gun has not been chronographed and is not regulated and I cannot get feedback from the targets due to the placement of the golf balls. My choices are JSB Jumbo heavy match 18.13 grains or crossman premier hollow points 14.3 grains. 


Question: what is the corresponding shorter site in difference for the gun that will hit the golf balls? Alternative question, if I cite it in for 17 yards what is the holdover to hit the golf balls?

ps I know I am missing a variable I am hoping one of you has it or close to it. 



 
Let's assume a velocity of 880 fps with the 18 gr pellet. You need to be around 3" high at 25 yards for that 78 yard zero. Alternatively, your 17 yard zero would require around an 8" hold over at 78. Like any chart information, it's generally correct, but never precisely correct. I doubt if it would put you within a couple of golf balls of your target, but maybe a starting point. Even if your zero is perfect, you are not going to hit a golf ball with every shot at 78 yards, so keep your expectations realistic. 
 
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Without a chronograph to measure your velocity you will have a very hard time trying to figure out your trajectory. Try setting targets out at 5 or 10 yd. increments and see how far the drop or rise is at each target as you shoot at the same bullseye at each distance. Then, using the rangeing marks in your scope,you will be able to use correct holdover or under for your shot if you know the distance to target. You can make up range card to use for reference in the field but as soon as your velocity changes or you use a different weight pellet your will have to re figure everything. If you plan on hunting or shooting at longer ranges it is a whole lot easier if you have a rangefinder and a chronograph! Good luck!

Bruce
 
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So what is the realistic max repeatable 1 inch radius distance?
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That depends on-You, the wind, You, Your rifle, You, your rest, You, your pellets....you get the idea. Set up targets at different ranges and see what happens in actual conditions.

As far as a zero distance, that's up to you as to whether you want to deal with hold under at the intermediate distances. Most Field target shooters zero for the apex of the trajectory so every adjustment in their hold is up.

By the way, golf balls can send the pellet back at you with enough velocity to be dangerous, you might be safe at 78 yards, but be advised!
 
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Also, why did you pick 880?
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I had to pick something. That is usually a good, and achievable velocity. As to repeatable 1" accuracy, that depends on all the variables involved, rifle, shooter, conditions, etc., impossible to give an opinion, especially knowing nothing of rifle or shooter. My guess, a broad-based average of all standard power rifles and all shooters, good conditions, somewhere between 50 and 70 yards. 
 
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Ponsoldt2, that's pretty far to expect to hit and 1.5-1.75" consistently with those unknown variables. Until you can get a chronograph and tune you need to at least find the sweet spot to fill the gun to. It would also be nice to know what you are filling to now and what the pressure is when you stop shooting and refill. After you refill the gun more than likely the first shots will be a lower velocity than the middle of the shot string (bell curve) and then and the end of your shooting range of pressure the velocity will be lower again. At 10-25yds this range variations of velocity probably won't be noticed but at 78yds will be very noticeable and account for a lot of the misses. 

What I would do if I was in your shoes would be to zero at 35-50yds first off, while the gun is in the middle of the pressure range between full and at your refill pressure, ex, if you fill to 230bar or what ever your max pressure allowed is and you stop shooting at 150bar you might do the zeroing at about 190bar and not at the top end or bottom end pressure. We're not sure how much you understand about the bell curve and its varying velocity of an unregulated gun so feel free to ask. 

Another thing you could do after zeroing at your 35-50yds and at in the middle of the fill range is take a piece of cardboard, maybe 20"X20" draw a bold black line with some hash marks across the middle. Refill the gun as you have been and make a note of that pressure. What I would do then is shoot 3-5 shots at the far left hash mark of that horizontal line, aiming at the line carefully. Then move over a couple of inches and shoot another 3-5 shots on the next hash mark on at the line. Continues this until you have shot 35-40 shots across the length of the line. Every 10shots record the best you can what the pressure is on your gauge. I expect what you'll see is on the far left your shots may be a little higher than the line and then as you continue to shoot you'll have a series of shots that are on or very closer to the line and then as you continue to shoot, the shots will start falling below the line. As you've been recording the pressures note where it was when you started getting the long series of "good" hits and the pressure at which they begin to fall below the line. These two pressures can now be your new fill and refill pressures to give you the best part of the bell curve. It'll also save you some air that was basically "wasted" by over filling and shooting it down too far. 

Doing the above will really help at the long distance shooting. This is just the start so don't expect to hit that golf ball every time until you learn more about your gun and it's capability by eliminating some of the variables. 

Jking


 
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@ponsoldt2 As stated by others. You really need a chrony. Download these 2 free apps and hopefully this will solve your problem.
Screenshot_20210131-095233.1612105031.png
Screenshot_20210131-095301.1612105048.png

 
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I guess I'm just old school and too mentally lazy for all this math and chrono stuff. (I do have and use a chrono though)
Hell, all you have to do is go back to your golf balls and set a big piece of cardboard behind them. Shoot for a group while aiming at the balls, then either adjust your scope to hit the balls or measure the amount of holdover you need to do.
 
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There has been some good advice on this thread. My unregulated .22 Mrod gen 2 came tuned from the factory shooting about 22.5 FPE, with the highest velocity coming in at 800 FPS shooting JSB 15.89’s at about a 2400 psi from a 3000 fill. I have since detuned it to a 750 fps tune with my sweet spot from 2400 to 1800 with about 25 shots all within 9 fps of each other. A chronograph sure is helpful in finding your sweet spot and for changing power levels, but a manual sweet spot determination system like jking discussed will work too and will tell you some things a chrono will not.
 
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Yes, to beat a horse before its dead... DON'T SHOOT real GOLF BALLS! The elasticity of the golf ball will return the pellet in random directions. That pellet is your responsibility until it stops moving. Any and all damages are yours due to lack of due diligence.

You are setting yourself up for endless frustration with your hanging target idea, shooting an unknown gun with.no direct experience to build on. Your learning curve is a vertical cliff. Walmart has a 4" metal target for about 12.00. it will make a nice little ping and may even move a little when you hit it. Suspend from an A frame with a few inches cleaned under the metal. Shoot, watch for splashed dirt, then make corrections.


 
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Look, you are over thinking your problem and likely asking a bit more than you can reasonably expect from your rifle. First figure out what your rifle is doing. Do that by shooting it at known ranges on paper. Keep careful logs of the readings on your pressure gauges, what pellets you are shooting, how many shots on a fill, etc. Keep your notes on your targets and save your targets. Date and time should be on every target as well. Get yourself a good history on your rifle BEFORE you try to shoot golf balls at 80 yards... and like other's have said, maybe pick something like a crushed tin can on a string rather than something that can bounce something back at you.

But first, get to know your rifle, that is an adventure in itself, I love putting my hands on a rifle I have never shot BECAUSE it represents a bunch of shooting and discovery. It's like getting to know a new friend or getting a new puppy. It's there just waiting for you to get to know it. If you do, it will do what you want, but first know it, then put it to work.

There is a way to figure out your velocity using a ballistics application. I did a video on it but have since deleted those Chairgun videos from the web. Basically you set up your rifle and pellet combination as carefully as you possibly can in something like Strealok or Chairgun. Once you have that you zero at a known distance and input that information into your app. Let's say 25 yards is where you zero and you have everything carefully entered in your app. Now set up a target another distance, preferably about twice as far, so lets say 40 yards. Shoot a group and document the exact difference between your impact point at 25 yards and your impact point at 40 yards. If you have everything else correct in your application there is only one velocity which will shoot to both points and all you have to do is guess at velocities until you get something that looks good. Now pick a third distance and check your work. It should also match up with no sight changes but only if the velocity you guessed is correct. Hope that makes sense.



EDIT: Using that method I have usually been able to guess my true muzzle velocity within about 20 fps.
 
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