Post by snyper on Nov 19, 2008 5:13:25 GMT 8
This article is from the yellow forum "How to set up your airgun (long)"
In Field Target or hunting, knowing how to hit a very small target at a previously unknown range with a single shot is the name of the game.
You do this by measuring the distance to your target using your rifle scope, then adjusting the elevation on your scope or by “holding over” (purposefully aiming above the target) to account for the pellet’s ballistics.
As with most things in life, you get what you’re willing to give. In order to hit your targets consistently every day regardless of range, you’ll need to at least set up your airgun / rifle combination very carefully.
This article presents a method for doing that. It is certainly not the only method, and for you it may not be the best method. However, it’s what I use when I’m setting up my guns, and it works well for me. At the 2006 Nationals, I was tied for ninth place at the end of the first day with a rifle I finished setting up in the hotel room the previous night.
EQUIPMENT USED:
I use a lot of equipment to set up my guns. I do this so that I can eliminate guesswork as a cause of errors.
1) The Vertical Reticule Instrument from Long Shot Products: This is a great device that will allow you to align the reticule on your scope with the bore of the barrel. In other words, it will let you set up your rifle / scope combination so that the scope’s elevation knob effects only elevation and the windage knob effects only windage. It will also allow you to attach a bubble level (or other product) to your rifle so that you can avoid cant when shooting.
www.microlevel.biz/vertical_retical_instrument.html
2) A Chronograph: I use the V1 Chrony, but you can use anything you want. If you’re serious at all about knowing your airgun, you need to get (or get access to) a chronograph. It’s that simple.
3) A scope Level. Ususally a bubble level with some method for attaching it to the scope. A cheap alternative is to remove the yellow cylinder of liquid from a line level, and glue it with silicone glue to something on your gun. I glue mine to the top of one of the scope mounts where I can easily see it.
4) Chairgun V2 software: This is a really useful product in all kinds of ways. We’re going to use it to establish a baseline for your gun’s performance. Along the way, we’ll also use it to calculate our scope height, and optimum zero range.
www.chairgun.com
5) A Level: You’ll use this with the Vertical Reticule Instrument.
6) A ruler, tape measure, caliper or other measuring instrument.
7) A padded vise, gun rest or other device for holding a gun safely without damaging it.
Optional (but recommended) equipment:
1) Range Tape software from www.airgunsoftware.com : A shameless plug for a peerless product.
2) A pellet sampler from straightshooters. You’ll want to know which pellet your gun likes. www.straightshooters.com
3) A soft, pull-through, barrel cleaning kit.
PROCESS:
Read all the instructions for each section before you begin:
1) Position your Scope:
to be accurate, you need to be comfortable. This step will insure that your scope is in the right position for your shooting style.
a. Attach the scope by carefully following the manufacturer’s directions for both the scope and your mounts. DON’T TIGHTEN IT DOWN COMPLETELY!
b. Now sit, kneel, or stand in the position you normally shoot from, and slide the scope forward or backward until you have proper eye relief (that is, until you can see correctly through the scope). This is important because if you have to strain to see through the scope your accuracy will suffer.
c. If you have an adjustable rifle, now is the time to make sure your adjustments allow you to see through the scope properly, while you are in your shooting position. Don’t bend yourself around the rifle, make sure you’ve adjusted everything you can to get the rifle to bend around you.
d. Once you’re comfortable with the placement of the scope, get it approximately level by turning the scope until the horizontal reticule line is about horizontal with the ground and the vertical reticule line connects the center of the scope with the center of the bore. Don’t worry about getting this too accurate, we’ll make it REALLY accurate later.
e. Now that the scope is roughly level, tighten it down enough so that you can shoot with it
f. Now get up and go do something else for 15 minutes or so. This is important! It will make your body forget the position you were in.
g. Has 15 minutes gone by yet? I didn’t think so.
h. Okay, now that some time has gone by, go back, pick up your gun, and shoot it at a close target to make sure your scope position is correct. By close, I mean 15 yards or less. We’re not worrying about accuracy here, just comfort.
i. If you find that you have to struggle to see through the scope correctly, grit your teeth, loosen up the scope and go back to step b.
2) Align your scope with your bore:
It is very important that your scope’s elevation adjustment only change the elevation of your shot. The only way to achieve this is to align the vertical crosshair in your scope with the bore of your airgun.
a. Make a note of where your scope is positioned. A small piece of tape on the scope barrel will be enough. You want to do this because you just spent a lot of time getting the scope positioned correctly, and you don’t want to lose that work when you…
b. Loosen the scope in the mounts just enough that you can rotate it with a little effort. You don’t want it too loose or you’ll bump it off level. Too tight and you won’t be able to turn it in small enough increments. Do your best.
c. Now put your gun in your gun rest or vise so that it is held securely.
d. Use the Vertical Reticule Instrument to align the scope with your bore according to the manufacturer’s directions. This consists of placing the instrument so that it contacts your scope and the barrel, then rotating the gun until the bubble in the instrument reads level. Then you want to look through the scope at a true vertical line. I drew one on the inside of my garage, but an effective method is to tape a meter long level vertically to something, and look through the scope at the edge of the level.
e. Once your scope is aligned properly, tighten the mounts again by tightening one screw a half turn or so, then proceeding to a screw on either the opposite side of the scope or the opposite mount or both. After you’ve partially tightened a few screws, recheck your level. If you tighten one side too much, you’ll rotate the scope and have to go back and re-level. So tighten a little, then check, then tighten a little etc. If you find the scope has rotated a little bit to one side, try tightening the screws on the other side to rotate it back. You may have to loosen the opposite screws a bit first.
3) Attach a scope level:
Use a scope level when you shoot. It does no good to have aligned your scope if you hold your airgun canted.
a. Once your gun is held securely with the leveling device showing level, you should attach your scope level. This is your only chance to do this because it’s the only time you can be positive everything is lined up properly.
4) OPTIONAL: Clean your barrel:
If your gun is new, or you’ve shot it for ever and never cleaned it, then give it a quick pass. It’s arguable that airgun barrels don’t need to be cleaned unless you regularly shoot unlubed pellets at velocities above 1000fps.
a. Clean Gently. Don’t overdo it. You’re not scrubbing down a crime scene. And don’t use anything really harsh. The rifling in an airgun barrel is very shallow and delicate. You don’t want to mess it up.
5) OPTIONAL: Find the pellet your gun likes best.
It’s a commonly held belief that any given airgun will shoot its tightest groups with a single brand / style / weight of pellet. Your job is to find that pellet.
a. Gather a bunch of pellets of different makes and weights. Don’t let what you’ve read bias you toward or away from any individual pellet. Let your rifle choose what it likes best.
b. Prepare the pellets in your pellet sampler the way you’ll prepare your final pellets. That is, oil them or wax them as you normally would (again, go easy!).
c. Shoot a bunch of different pellets in windless conditions at a target that’s between 25 and 35 yards away. Smallest group wins.
d. Acquire an adequate supply of the best pellets, and prepare them appropriately.
6) Find out how fast your gun shoots:
You need to know this to know how to adjust your scope for distance.
a. Once you’ve selected a pellet, shoot some over the chrony. Make sure you follow the manufacturer’s directions for the chronograph!
TIPS:
7) Find the “meat” of the power curve:
This is important so that you know how much air to put in your gun, what velocity it shoots at, and how many shots you’ve got.
a. This only applies to PCP guns. Springer owners can skip this section.
b. This will take some time and require some patience.
c. First fill the gun to a high pressure. Don’t exceed (or even come very close to) the manufacturer’s specifications, but you want a pressure that’s too high to be efficient. I have a Daystate that’s rated for 250 bar. I fill it to about 200 bar for this test.
d. Later you’ll need to refill the gun to this pressure, so write the value down (or remember if you’re under 40).
e. Now, shoot across the chrony and record each shot number along with the velociy. You’re going to shoot until most of your fill is gone, so it may take a while depending on your gun and power setting.
f. What you’ll notice is that the velocity will rise at first, may or may not stabilize, then start to fall. Slowly at first, then more rapidly. If you have a regulated rifle, you’ll see the velocity rise very quickly, stabilize for a long time (probably rising slightly toward the end) then fall off like switch got thrown.
g. Examine the whole shot string (a spreadsheet program helps) and find the place where the rising curve flattens out, and figure out how many shots it took to get there. If you kept track of each shot, this should be easy. Call this shot number X.
h. Also, find the place where the velocity starts to fall off quickly, or where it drops below a reasonable value. Call this shot number Y.
i. Average the velocities you got between shot number X and shot number Y. This is the velocity you’ll use in Chairgun.
j. Now that you know your gun has Y-X consistent shots per fill, the next step will be to figure out the optimum fill pressure. Fill your gun back up to the high pressure you recorded earlier, and shoot X number of shots (the number of shots from step g).
k. If you have a gauge on your gun, you’ll be able to see what the pressure is. If you don’t have a gauge on your gun, just connect your gun to the tank and slowly open the tank until the valve pops open. Quickly close the valve, then you can read the pressure from the gauge.
l. This is your optimum fill pressure. Next time you fill your gun, only fill it to this pressure.
m. From this pressure you have Y-X shots (from step i).
8) Get acquainted with Chairgun:
A very useful program. We’re just going to scratch the surface of what it can tell you.
a. Fire up Chairgun.
b. Click the “pellet 1” button and select your pellet from the list. If your pellet isn’t in the database, you can look up its mass and BC in a variety of places. Here’s one, but there are others:
www.airgunexpo.com/airgundb/pelletbc.cfm
9) Scope Height:
what we care about is the height of the scope above the muzzle. This is something that’s difficult to measure. Fortunately, Chairgun 2 gives us some tools to calculate the value.
a. First, draw 5 or 6 dark, one half inch X’s in a horizontal line on a piece of white paper. We’ll use this as a target to calculate our real scope height. But first, we have to figure out how far away to place the target.
b. Using your ruler or caliper, measure the height from the center of the barrel to the center of the scope. This will ordinarily be between 1 and 2 inches, although it will certainly vary widely.
c. Bring up Chairgun again.
d. Click the “Scope” button and in the top box (height) enter the value you measured in step “b” above.
e. In the bottom box, enter the number of clicks your scope requires to move one minute of angle (MOA). This is usually 8.34 for 1/8” click scopes and half that for 1/4” click scopes.
f. Click the close button, you’re done with this dialog.
g. Now go to the “Extras” menu and select optimum zero range.
h. When the dialog box comes up, click “scope”. The dialog will fill in the five ranges.
i. Write down the range for “Zenith Distance”, and close the dialog.
j. Set up the target as close to the “Zenith Distance” as you can. This is usually near 30 yards or so.
k. Shoot at one of the X’s and adjust your scope until your group centers around the middle of the X.
l. Now, move the target in until it’s at about half the distance to the “Zenith Range”.
m. Okay, WITHOUT ADJUSTING YOUR SCOPE’S ELEVATION, aim at one of the X’s on the target.
n. Shoot 3-5 shots while aimed at the X. your shots should all strike the target below the center of the X. Don’t worry about it, this is what you want.
o. Repeat this with the remaining X’s.
p. Now take your measuring device and measure the average distance from the center of each X to the group you shot at that X.
q. Average the distances you’ve measured.
r. Back in Chairgun, go to “Calibrate” then “Fine Tuning” then “Tune Scope Height”.
s. Enter the range of the closer target (should be around 15 yards) in the top box “Test Range”. Now take the average distance you calculated in step “q” above, and enter it as a negative number in the bottom box “Measured POI”.
t. Click the “close” button and the dialog will adjust your scope height to match your measurements.
10) Ranging
With the new scope height, Chairgun’s calculations should be relatively accurate, but we can still do a little fine tuning.
11) OPTIONAL: Make an accurate range tape for your scope.
Now go out and do some shooting, you’ve been working too hard!!!
In Field Target or hunting, knowing how to hit a very small target at a previously unknown range with a single shot is the name of the game.
You do this by measuring the distance to your target using your rifle scope, then adjusting the elevation on your scope or by “holding over” (purposefully aiming above the target) to account for the pellet’s ballistics.
As with most things in life, you get what you’re willing to give. In order to hit your targets consistently every day regardless of range, you’ll need to at least set up your airgun / rifle combination very carefully.
This article presents a method for doing that. It is certainly not the only method, and for you it may not be the best method. However, it’s what I use when I’m setting up my guns, and it works well for me. At the 2006 Nationals, I was tied for ninth place at the end of the first day with a rifle I finished setting up in the hotel room the previous night.
EQUIPMENT USED:
I use a lot of equipment to set up my guns. I do this so that I can eliminate guesswork as a cause of errors.
1) The Vertical Reticule Instrument from Long Shot Products: This is a great device that will allow you to align the reticule on your scope with the bore of the barrel. In other words, it will let you set up your rifle / scope combination so that the scope’s elevation knob effects only elevation and the windage knob effects only windage. It will also allow you to attach a bubble level (or other product) to your rifle so that you can avoid cant when shooting.
www.microlevel.biz/vertical_retical_instrument.html
2) A Chronograph: I use the V1 Chrony, but you can use anything you want. If you’re serious at all about knowing your airgun, you need to get (or get access to) a chronograph. It’s that simple.
3) A scope Level. Ususally a bubble level with some method for attaching it to the scope. A cheap alternative is to remove the yellow cylinder of liquid from a line level, and glue it with silicone glue to something on your gun. I glue mine to the top of one of the scope mounts where I can easily see it.
4) Chairgun V2 software: This is a really useful product in all kinds of ways. We’re going to use it to establish a baseline for your gun’s performance. Along the way, we’ll also use it to calculate our scope height, and optimum zero range.
www.chairgun.com
5) A Level: You’ll use this with the Vertical Reticule Instrument.
6) A ruler, tape measure, caliper or other measuring instrument.
7) A padded vise, gun rest or other device for holding a gun safely without damaging it.
Optional (but recommended) equipment:
1) Range Tape software from www.airgunsoftware.com : A shameless plug for a peerless product.
2) A pellet sampler from straightshooters. You’ll want to know which pellet your gun likes. www.straightshooters.com
3) A soft, pull-through, barrel cleaning kit.
PROCESS:
Read all the instructions for each section before you begin:
1) Position your Scope:
to be accurate, you need to be comfortable. This step will insure that your scope is in the right position for your shooting style.
a. Attach the scope by carefully following the manufacturer’s directions for both the scope and your mounts. DON’T TIGHTEN IT DOWN COMPLETELY!
b. Now sit, kneel, or stand in the position you normally shoot from, and slide the scope forward or backward until you have proper eye relief (that is, until you can see correctly through the scope). This is important because if you have to strain to see through the scope your accuracy will suffer.
c. If you have an adjustable rifle, now is the time to make sure your adjustments allow you to see through the scope properly, while you are in your shooting position. Don’t bend yourself around the rifle, make sure you’ve adjusted everything you can to get the rifle to bend around you.
d. Once you’re comfortable with the placement of the scope, get it approximately level by turning the scope until the horizontal reticule line is about horizontal with the ground and the vertical reticule line connects the center of the scope with the center of the bore. Don’t worry about getting this too accurate, we’ll make it REALLY accurate later.
e. Now that the scope is roughly level, tighten it down enough so that you can shoot with it
f. Now get up and go do something else for 15 minutes or so. This is important! It will make your body forget the position you were in.
g. Has 15 minutes gone by yet? I didn’t think so.
h. Okay, now that some time has gone by, go back, pick up your gun, and shoot it at a close target to make sure your scope position is correct. By close, I mean 15 yards or less. We’re not worrying about accuracy here, just comfort.
i. If you find that you have to struggle to see through the scope correctly, grit your teeth, loosen up the scope and go back to step b.
2) Align your scope with your bore:
It is very important that your scope’s elevation adjustment only change the elevation of your shot. The only way to achieve this is to align the vertical crosshair in your scope with the bore of your airgun.
a. Make a note of where your scope is positioned. A small piece of tape on the scope barrel will be enough. You want to do this because you just spent a lot of time getting the scope positioned correctly, and you don’t want to lose that work when you…
b. Loosen the scope in the mounts just enough that you can rotate it with a little effort. You don’t want it too loose or you’ll bump it off level. Too tight and you won’t be able to turn it in small enough increments. Do your best.
c. Now put your gun in your gun rest or vise so that it is held securely.
d. Use the Vertical Reticule Instrument to align the scope with your bore according to the manufacturer’s directions. This consists of placing the instrument so that it contacts your scope and the barrel, then rotating the gun until the bubble in the instrument reads level. Then you want to look through the scope at a true vertical line. I drew one on the inside of my garage, but an effective method is to tape a meter long level vertically to something, and look through the scope at the edge of the level.
e. Once your scope is aligned properly, tighten the mounts again by tightening one screw a half turn or so, then proceeding to a screw on either the opposite side of the scope or the opposite mount or both. After you’ve partially tightened a few screws, recheck your level. If you tighten one side too much, you’ll rotate the scope and have to go back and re-level. So tighten a little, then check, then tighten a little etc. If you find the scope has rotated a little bit to one side, try tightening the screws on the other side to rotate it back. You may have to loosen the opposite screws a bit first.
3) Attach a scope level:
Use a scope level when you shoot. It does no good to have aligned your scope if you hold your airgun canted.
a. Once your gun is held securely with the leveling device showing level, you should attach your scope level. This is your only chance to do this because it’s the only time you can be positive everything is lined up properly.
4) OPTIONAL: Clean your barrel:
If your gun is new, or you’ve shot it for ever and never cleaned it, then give it a quick pass. It’s arguable that airgun barrels don’t need to be cleaned unless you regularly shoot unlubed pellets at velocities above 1000fps.
a. Clean Gently. Don’t overdo it. You’re not scrubbing down a crime scene. And don’t use anything really harsh. The rifling in an airgun barrel is very shallow and delicate. You don’t want to mess it up.
5) OPTIONAL: Find the pellet your gun likes best.
It’s a commonly held belief that any given airgun will shoot its tightest groups with a single brand / style / weight of pellet. Your job is to find that pellet.
a. Gather a bunch of pellets of different makes and weights. Don’t let what you’ve read bias you toward or away from any individual pellet. Let your rifle choose what it likes best.
b. Prepare the pellets in your pellet sampler the way you’ll prepare your final pellets. That is, oil them or wax them as you normally would (again, go easy!).
c. Shoot a bunch of different pellets in windless conditions at a target that’s between 25 and 35 yards away. Smallest group wins.
d. Acquire an adequate supply of the best pellets, and prepare them appropriately.
6) Find out how fast your gun shoots:
You need to know this to know how to adjust your scope for distance.
a. Once you’ve selected a pellet, shoot some over the chrony. Make sure you follow the manufacturer’s directions for the chronograph!
TIPS:
7) Find the “meat” of the power curve:
This is important so that you know how much air to put in your gun, what velocity it shoots at, and how many shots you’ve got.
a. This only applies to PCP guns. Springer owners can skip this section.
b. This will take some time and require some patience.
c. First fill the gun to a high pressure. Don’t exceed (or even come very close to) the manufacturer’s specifications, but you want a pressure that’s too high to be efficient. I have a Daystate that’s rated for 250 bar. I fill it to about 200 bar for this test.
d. Later you’ll need to refill the gun to this pressure, so write the value down (or remember if you’re under 40).
e. Now, shoot across the chrony and record each shot number along with the velociy. You’re going to shoot until most of your fill is gone, so it may take a while depending on your gun and power setting.
f. What you’ll notice is that the velocity will rise at first, may or may not stabilize, then start to fall. Slowly at first, then more rapidly. If you have a regulated rifle, you’ll see the velocity rise very quickly, stabilize for a long time (probably rising slightly toward the end) then fall off like switch got thrown.
g. Examine the whole shot string (a spreadsheet program helps) and find the place where the rising curve flattens out, and figure out how many shots it took to get there. If you kept track of each shot, this should be easy. Call this shot number X.
h. Also, find the place where the velocity starts to fall off quickly, or where it drops below a reasonable value. Call this shot number Y.
i. Average the velocities you got between shot number X and shot number Y. This is the velocity you’ll use in Chairgun.
j. Now that you know your gun has Y-X consistent shots per fill, the next step will be to figure out the optimum fill pressure. Fill your gun back up to the high pressure you recorded earlier, and shoot X number of shots (the number of shots from step g).
k. If you have a gauge on your gun, you’ll be able to see what the pressure is. If you don’t have a gauge on your gun, just connect your gun to the tank and slowly open the tank until the valve pops open. Quickly close the valve, then you can read the pressure from the gauge.
l. This is your optimum fill pressure. Next time you fill your gun, only fill it to this pressure.
m. From this pressure you have Y-X shots (from step i).
8) Get acquainted with Chairgun:
A very useful program. We’re just going to scratch the surface of what it can tell you.
a. Fire up Chairgun.
b. Click the “pellet 1” button and select your pellet from the list. If your pellet isn’t in the database, you can look up its mass and BC in a variety of places. Here’s one, but there are others:
www.airgunexpo.com/airgundb/pelletbc.cfm
9) Scope Height:
what we care about is the height of the scope above the muzzle. This is something that’s difficult to measure. Fortunately, Chairgun 2 gives us some tools to calculate the value.
a. First, draw 5 or 6 dark, one half inch X’s in a horizontal line on a piece of white paper. We’ll use this as a target to calculate our real scope height. But first, we have to figure out how far away to place the target.
b. Using your ruler or caliper, measure the height from the center of the barrel to the center of the scope. This will ordinarily be between 1 and 2 inches, although it will certainly vary widely.
c. Bring up Chairgun again.
d. Click the “Scope” button and in the top box (height) enter the value you measured in step “b” above.
e. In the bottom box, enter the number of clicks your scope requires to move one minute of angle (MOA). This is usually 8.34 for 1/8” click scopes and half that for 1/4” click scopes.
f. Click the close button, you’re done with this dialog.
g. Now go to the “Extras” menu and select optimum zero range.
h. When the dialog box comes up, click “scope”. The dialog will fill in the five ranges.
i. Write down the range for “Zenith Distance”, and close the dialog.
j. Set up the target as close to the “Zenith Distance” as you can. This is usually near 30 yards or so.
k. Shoot at one of the X’s and adjust your scope until your group centers around the middle of the X.
l. Now, move the target in until it’s at about half the distance to the “Zenith Range”.
m. Okay, WITHOUT ADJUSTING YOUR SCOPE’S ELEVATION, aim at one of the X’s on the target.
n. Shoot 3-5 shots while aimed at the X. your shots should all strike the target below the center of the X. Don’t worry about it, this is what you want.
o. Repeat this with the remaining X’s.
p. Now take your measuring device and measure the average distance from the center of each X to the group you shot at that X.
q. Average the distances you’ve measured.
r. Back in Chairgun, go to “Calibrate” then “Fine Tuning” then “Tune Scope Height”.
s. Enter the range of the closer target (should be around 15 yards) in the top box “Test Range”. Now take the average distance you calculated in step “q” above, and enter it as a negative number in the bottom box “Measured POI”.
t. Click the “close” button and the dialog will adjust your scope height to match your measurements.
10) Ranging
With the new scope height, Chairgun’s calculations should be relatively accurate, but we can still do a little fine tuning.
11) OPTIONAL: Make an accurate range tape for your scope.
- Get the free Range Tape program and follow the directions to create a tape that you can affix to your scope. This tape will let you very accurately measure distances using your rifle scope.
Now go out and do some shooting, you’ve been working too hard!!!
