Chairgun optimum zero
- Thread starter tsmith
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Optimum zero in Chairgun is intended to set you up so that your projectile rises to line of sight, crosses it and goes above line of sight and then drops until it crosses it and goes below line of sight. Why? Suppose you shoot at a target the size of a golf ball. You are in the field and you have no means of estimating range accurately. You want to set up your rifle so that you can aim at the center of the ball and have the pellet strike the ball anywhere on it. Essentially you establish a BRACKET of ranges wherein that pellet will hit the ball if you aim at the center of your target (golf ball).
There will be some range at which the pellet has risen enough to hit the bottom of the ball. That range is the near edge or closest range. There will be a range at which the pellet has risen above line of sight and will just hit the top of the ball. This is close to (not exactly) at the center of your bracket. There will be a range at which the pellet has dropped where it will just hit the bottom of the ball. That is the far edge or farthest range of the bracket. This "range bracket" is established by setting the FAR zero (second point where the pellet crosses zero line) so that the longest distance is covered in the bracket.
Said another way. The optimum zero is that point at which the pellet crosses the line of sight on its way DOWN from the highest point of flight above the line of sight. The range bracket or effective range or zero zone is that spread of distance between which the pellet will strike the bottom of the target zone as it rises towards line of sight and where it will strike the same point after it has again fallen below line of sight.
Let me offer a link (you are interested in #3):
https://www.youtube.com/watch?v=SxQgUL3qLws&list=PL5-WDa6lLRrKeUem6oszoPp_NSfqX0vI7
There will be some range at which the pellet has risen enough to hit the bottom of the ball. That range is the near edge or closest range. There will be a range at which the pellet has risen above line of sight and will just hit the top of the ball. This is close to (not exactly) at the center of your bracket. There will be a range at which the pellet has dropped where it will just hit the bottom of the ball. That is the far edge or farthest range of the bracket. This "range bracket" is established by setting the FAR zero (second point where the pellet crosses zero line) so that the longest distance is covered in the bracket.
Said another way. The optimum zero is that point at which the pellet crosses the line of sight on its way DOWN from the highest point of flight above the line of sight. The range bracket or effective range or zero zone is that spread of distance between which the pellet will strike the bottom of the target zone as it rises towards line of sight and where it will strike the same point after it has again fallen below line of sight.
Let me offer a link (you are interested in #3):
https://www.youtube.com/watch?v=SxQgUL3qLws&list=PL5-WDa6lLRrKeUem6oszoPp_NSfqX0vI7
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It tells you the optimum zero to shoot point blank at the largest range of distances given your pellet velocity and kill zone size.
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so what is near and far PBR? how is it different from near/far zero?
if i want NO hold unders,(dont want my poi to ever be above the crosshair) is my best bet to enter 0.1” for the kill zone?
and if i do that, is zenith my sight in range? thats how i understand it anyway.
thanks for the help.
if i want NO hold unders,(dont want my poi to ever be above the crosshair) is my best bet to enter 0.1” for the kill zone?
and if i do that, is zenith my sight in range? thats how i understand it anyway.
thanks for the help.
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Near point blank range is the closest the object can be and still hit it with your zero without holdover or under. Far point bland range would be the farthest you'd still hit the target. The smaller the kill zone, the shorter the PBR will be. Entering .1" will give a very short range of PBR values.
Choose "Single Zero Range" if you want no hold unders and a single zero point.
Choose "Single Zero Range" if you want no hold unders and a single zero point.
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Here is an example using all the same data but changing from the Optimum range (2 zeros) to the Single zero range. Notice that the overall PBR is shorter for the single zero range.
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Yes. If you want to set a zero stop and always click for the range, you can enter 0.01 for the kill zone dimension. Then when you click the "optimum zero range" from the toolbox, it will show the near/ far zero as the same.
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There are some tricks to making Chairgun work better than just using a measured scope height and the listed BC. Start with the listed BC and weight for your projectile either in Chairgun or from the web and the muzzle velocity and enter a good estimate of your scope height.
Zero the scope at the first zero of 20 yards which is a range where minimal drop will have occurred.
Zero the scope at 20 yards and enter that as the input to chairgun
Take note of the elevation setting on the turret.
Enter 10 yards as the zero in Chairgun. Read the chart as to what it says the clicks will be.
Zero at 10 yards (hopefully your scope can come up to this) and compare on the chart the number of clicks that it told you to use, and the number of clicks that you actually used. 15 yards could work but wouldn't have as much resolution as at 10 yards. 12 1/4 moa clicks for 15 yards versus 45 clicks for example.
Adjust the value of scope height in Chairgun until the chart matches the actual value of clicks that you found. This is what Chairgun thinks your scope height is. I have found that this might be quite a bit different than what you can measure for some reason.
Now to get the BC set as best: Stretch out the range as far as you might want to shoot/ have room for/ can still get a reasonable group, in 5 yard increments. 50-60 yards at least. Compare the actual clicks to what Chairgun predicted as the difference from 20 yards and adjust the BC entry until they match. This is essentially the same as using the POI drop calculator for BC from the toolbox.
When you are done with these calibration steps you can then calculate the zero that you may want according to Chairgun and the fly through of the point of impact and your desired kill zone tolerance using the "optimum zero range" button under the toolbox tab.
I usually set a .5" kill zone and then remember I am 1/4" low at 13 yards, 1/4" high at 35, and 1/4" low at 40 for example with my Mrod .177 with it's low scope height so that I don't have to click within those ranges. If you use a zero stop and never want to hold or click "under", set the kill zone to 0.01" and the near and far zero will be the same with no point of impact above..
.
There are some tricks to making Chairgun work better than just using a measured scope height and the listed BC. Start with the listed BC and weight for your projectile either in Chairgun or from the web and the muzzle velocity and enter a good estimate of your scope height.
Zero the scope at the first zero of 20 yards which is a range where minimal drop will have occurred.
Zero the scope at 20 yards and enter that as the input to chairgun
Take note of the elevation setting on the turret.
Enter 10 yards as the zero in Chairgun. Read the chart as to what it says the clicks will be.
Zero at 10 yards (hopefully your scope can come up to this) and compare on the chart the number of clicks that it told you to use, and the number of clicks that you actually used. 15 yards could work but wouldn't have as much resolution as at 10 yards. 12 1/4 moa clicks for 15 yards versus 45 clicks for example.
Adjust the value of scope height in Chairgun until the chart matches the actual value of clicks that you found. This is what Chairgun thinks your scope height is. I have found that this might be quite a bit different than what you can measure for some reason.
Now to get the BC set as best: Stretch out the range as far as you might want to shoot/ have room for/ can still get a reasonable group, in 5 yard increments. 50-60 yards at least. Compare the actual clicks to what Chairgun predicted as the difference from 20 yards and adjust the BC entry until they match. This is essentially the same as using the POI drop calculator for BC from the toolbox.
When you are done with these calibration steps you can then calculate the zero that you may want according to Chairgun and the fly through of the point of impact and your desired kill zone tolerance using the "optimum zero range" button under the toolbox tab.
I usually set a .5" kill zone and then remember I am 1/4" low at 13 yards, 1/4" high at 35, and 1/4" low at 40 for example with my Mrod .177 with it's low scope height so that I don't have to click within those ranges. If you use a zero stop and never want to hold or click "under", set the kill zone to 0.01" and the near and far zero will be the same with no point of impact above..
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i only have the iphone version. dont think there is a single zero option.
whats the difference between pbr range and near far zero?
whats the difference between pbr range and near far zero?
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PBR is the range of distances that the pellet will land within your kill zone. Near and far zero are the exact 2 distances that the pellet will land exactly on the point of aim.
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In Air Gun Field Target ( Hunter class ) we use 1 zero that being the pellets apex of flight that generally falls in the 24-30 yard range pending optics height.
Set as such, EVERY distance + or - your established zero range window / distance will become an increasing hold over value further you shoot and reverse increasing closer you shoot.
So lets just say your zero range on chair gun says to use 28 yards and you have selected a PBR of 1/4" .... So long as projectiles fight is +/- 1/8" of that your holding dead center.
That could be @ 23 yards to 33 yards.
Distances closer than 23Y will require HOLD OVER and distances past 32Y will require HOLD OVER ..... at no time is hold UNDER used.
Set as such, EVERY distance + or - your established zero range window / distance will become an increasing hold over value further you shoot and reverse increasing closer you shoot.
So lets just say your zero range on chair gun says to use 28 yards and you have selected a PBR of 1/4" .... So long as projectiles fight is +/- 1/8" of that your holding dead center.
That could be @ 23 yards to 33 yards.
Distances closer than 23Y will require HOLD OVER and distances past 32Y will require HOLD OVER ..... at no time is hold UNDER used.
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