I fight these questions a lot....
Is my chronograph really right? Which way is the sun shining on it to be correct??
How close is the published BC on that bullet??
Here's how to find out the truth on either or both...
First, get an accurate load worked up, this is not a test for load development. Make sure your gun is exactly like you are gonna be shooting it, we are not testing scopes, bedding etc, this is JUST a test to get true dope on your chosen load.
Bring the following to at least a 500 yard range, 600 is better.
1. 50 rounds of your chosen load.
2. Bring at least 10 feet of good wide paper, a continuous roll is best (wish I would have used it), staplegun, etc.
3. A good clear target you can shoot at full distance (I made one that works good at both 100 and 600).
4. Target backer at least tall enough to catch your full bullet travel at distance.
5. A Kestrel or some other way to get true temp and weather data (Density Altitude is best).
6. Ballistic Calculator (I use Shooter on my phone, but you can come home and do it on JBM after shooting, if you need to).
7. Gun and shooting needs.
8. A way to get accurate ranges to target, either a good rangefinder or measured accurate distances to target.
9. A chronograph is nice, but not necessary, you will be tweaking velocity anyway, but it will save some time and get you close quicker.
10. A tape measure and a level (2-3').
Watch the weather, you need to go to the range when it is as calm as possible, and most important, more than wind, is NO MIRAGE, do it very early or very late in the day, or very cloudy. A little wind (under 5-8 mph) is not too bad, but mirage will pretty much blow the test.
You want to eliminate as many variables as possible during the test, ie. always shoot in the same position, don't shoot prone at 100 and off a bench at 600, etc. I even placed my bipod legs on my padded shooting mat, instead of the ground (which is better), because I was on dirt on some ranges and gravel at another, etc.
Do NOT touch your scope during the test, this is NOT a scope test, leave it at your 100 yard zero.
Get the target set up as shown below, make sure you have enough paper below the target to catch your max bullet drop.
Get set up at 100 yards and shoot a few at a "waster" target to get rid of the jitter's and make sure you are shooting good, don't worry about a "perfect" zero, as it doesn't really matter, just so you are close and shooting a good GROUP.
NOTE CAREFULLY ALL WEATHER CONDITIONS, write them down!!
Shoot a 5 shot group at the center of your target (100 and full distance need at least a 5 shot group, 3 shots are OK for intermediate distances to reduce fatigue and make the test go as fast as possible, to negate changing weather conditions).
DO NOT TOUCH YOUR SCOPE DURING THE TEST!!!
Go to 200 yards (double check the distance), dry fire a few times to check NPA, shoot 3-5 shots at THE SAME aiming point you used at 100 yards, DO NOT hold for wind, horizontal dispersion is not important.
300, 400, and 500 yards--repeat.
Final distance, (600 yards in my case) shoot at least 5 shots, preferably 8 or 10, as this distance is most important.
Set up your chronograph and check your velocity with at least 5 shots, write it down, don't forget to add about 8 fps if your chrono is 10 ft. from muzzle.
Find and mark the center of each group...this is not easy to just eyeball, I have an app on my phone called "Target Calculator" that lets me take a pic and plot the shots and then shows true group center.
Take your level and make a horizontal line through each group center. As you can see, I had a slight prevailing 3-5mph wind (with occ. 10mph gusts, as you can see on the horz. group dispersion) from left to right, and you want to measure true DROP, DIRECTLY BELOW your top target, NOT to the group center.
Measure down from your 100 yard group center to each of your horizontal lines and this will be your true drop at each distance.
Now you have REAL dope...plug all the weather variables and other data into your ballistics program, now you can tweak the BC and velocity until you get the data to meet up with the real world.
Unless BOTH BC and Velocity are very close, you can hit the 100 and the 600 but the middle ranges will be off.
All mine hit exactly to the tenth of an inch after much tweaking of velocity and BC, except my 300 yard which was .4" tenths off and you can see the wind was howling then, I should have shot 5 shots instead of 3.
Is my chronograph really right? Which way is the sun shining on it to be correct??
How close is the published BC on that bullet??
Here's how to find out the truth on either or both...
First, get an accurate load worked up, this is not a test for load development. Make sure your gun is exactly like you are gonna be shooting it, we are not testing scopes, bedding etc, this is JUST a test to get true dope on your chosen load.
Bring the following to at least a 500 yard range, 600 is better.
1. 50 rounds of your chosen load.
2. Bring at least 10 feet of good wide paper, a continuous roll is best (wish I would have used it), staplegun, etc.
3. A good clear target you can shoot at full distance (I made one that works good at both 100 and 600).
4. Target backer at least tall enough to catch your full bullet travel at distance.
5. A Kestrel or some other way to get true temp and weather data (Density Altitude is best).
6. Ballistic Calculator (I use Shooter on my phone, but you can come home and do it on JBM after shooting, if you need to).
7. Gun and shooting needs.
8. A way to get accurate ranges to target, either a good rangefinder or measured accurate distances to target.
9. A chronograph is nice, but not necessary, you will be tweaking velocity anyway, but it will save some time and get you close quicker.
10. A tape measure and a level (2-3').
Watch the weather, you need to go to the range when it is as calm as possible, and most important, more than wind, is NO MIRAGE, do it very early or very late in the day, or very cloudy. A little wind (under 5-8 mph) is not too bad, but mirage will pretty much blow the test.
You want to eliminate as many variables as possible during the test, ie. always shoot in the same position, don't shoot prone at 100 and off a bench at 600, etc. I even placed my bipod legs on my padded shooting mat, instead of the ground (which is better), because I was on dirt on some ranges and gravel at another, etc.
Do NOT touch your scope during the test, this is NOT a scope test, leave it at your 100 yard zero.
Get the target set up as shown below, make sure you have enough paper below the target to catch your max bullet drop.
Get set up at 100 yards and shoot a few at a "waster" target to get rid of the jitter's and make sure you are shooting good, don't worry about a "perfect" zero, as it doesn't really matter, just so you are close and shooting a good GROUP.
NOTE CAREFULLY ALL WEATHER CONDITIONS, write them down!!
Shoot a 5 shot group at the center of your target (100 and full distance need at least a 5 shot group, 3 shots are OK for intermediate distances to reduce fatigue and make the test go as fast as possible, to negate changing weather conditions).
DO NOT TOUCH YOUR SCOPE DURING THE TEST!!!
Go to 200 yards (double check the distance), dry fire a few times to check NPA, shoot 3-5 shots at THE SAME aiming point you used at 100 yards, DO NOT hold for wind, horizontal dispersion is not important.
300, 400, and 500 yards--repeat.
Final distance, (600 yards in my case) shoot at least 5 shots, preferably 8 or 10, as this distance is most important.
Set up your chronograph and check your velocity with at least 5 shots, write it down, don't forget to add about 8 fps if your chrono is 10 ft. from muzzle.
Find and mark the center of each group...this is not easy to just eyeball, I have an app on my phone called "Target Calculator" that lets me take a pic and plot the shots and then shows true group center.
Take your level and make a horizontal line through each group center. As you can see, I had a slight prevailing 3-5mph wind (with occ. 10mph gusts, as you can see on the horz. group dispersion) from left to right, and you want to measure true DROP, DIRECTLY BELOW your top target, NOT to the group center.
Measure down from your 100 yard group center to each of your horizontal lines and this will be your true drop at each distance.
Now you have REAL dope...plug all the weather variables and other data into your ballistics program, now you can tweak the BC and velocity until you get the data to meet up with the real world.
Unless BOTH BC and Velocity are very close, you can hit the 100 and the 600 but the middle ranges will be off.
All mine hit exactly to the tenth of an inch after much tweaking of velocity and BC, except my 300 yard which was .4" tenths off and you can see the wind was howling then, I should have shot 5 shots instead of 3.
