Truing your muzzle velocity is an important step for achieving shooting accuracy, though I often hear shooters say that they skip it. I've found that the ones who tend to skip that step, are also, frequently, the same shooters that then talk about missing the mark at long range shots.
Then, of course, there are the very thorough shooters that methodically move back a KD range 100 yards at a time building out their DOPE. We have all seen them (and been them at one time or another), taking notes at each yard marker, sending bullet after bullet down range. The amount of ammo used is huge and the data really does not travel well. That same shooter can not pack up their rifle and expect the same DOPE to work on their Elk hunt in Idaho when the density altitude could have a shift of over 3000 ft. That is over a half a mil at just 1000 yards and could be the difference between a hit and a long, empty-handed ride back to camp -- or even worse, a lengthy hike tracking a wounded animal. MV truing can save you not only ammo, but also from those unwanted outcomes by improving your accuracy whether at the range or on a hunt.
Anytime that you are going to stretch the limits of your rifle into Subsonic ranges you are going to want to True your MV. I can't give one distance because it varies from caliber to caliber, rifle to rifle, barrel to barrel, etc.
What about getting my MV from a chronograph?
I have, love, and use both the MagnetoSpeed and LabRadar. They are great chronographs at a good price and give good data. I like to use mine more for the SD of my bullets, I do not use them for my true muzzle velocity and they are not a standard part of my range kit. I use them as a starting point for my MV and then go through the trueing process. It may only change the MV by a few FPS, but that makes a big difference in shooting long range. You do not need a chronograph at all when using the Kestrel 5700 with Applied Ballistics; the trueing process will give you a true muzzle velocity for that gun profile.
Take the Time to True
Truing is not hard and takes only a few rounds. First, you MUST get a good zero. We hear time and time again that garbage in = garbage out and that is very true. Your 100 yard zero sets the tone for all future shots – take the time to get it right. Many shooters shoot through more ammo confirming zero then they do truing.
How to True MV
Now, I will go into the steps that you use to true on your Kestrel. As we have mentioned in the past, I am Katie from Kestrel and my shooting career lives in my little custom pink Kestrel Elite with Applied Ballistics.
After confirming your zero be sure to "CRUSH" it.
Capture your direction of fire
Range the distance to the target
Update the wind speed and direction
Spin to update environmental. After you spin, be sure to change the update to LOCK!
Hit the target! – Ok, we will work on that in the Cal MV section
Enter your gun profile by pressing the center button and then go into MV. Scroll down to Cal MV and use the center button to enter. The display will now look like this:
The top right corner is giving you the yardage that your gun profile will go to Transonic. It is important to get within 15% of transonic without going over when you true. Think Price is Right rules. Find a target that is within that 15% range. With the selected target, be sure that it is one that has a good berm behind it. You must be able to see impact to adjust your shot. If your target is far ahead of the berm, or with high grass on the berm, find another place. My favorite is a rock. Rocks are great. You know that they are lying on the ground so there is no depth perception issues and you can see impact on and around it.
Adjust the yardage in the "Range" by using the left and right buttons.
Use the hold provided on the "Drop…" line to dial in your hold.
Take Your Shot
It is critical to get your elevation on – so a miss just off the right edge and then a miss just off the left edge is still good for a true. (Not so great on your wind calls but that is a different article) Missing above and then below – not so much! Go for a 3 round group minimum. 5 is even better. Remember the chronograph could have shown you that your lot of ammo may have some fliers so a single miss may not indicate a different hold. A good spotter is probably the number one thing that you need here – someone you trust that can talk your language, whether it is mils, inches, target widths, etc. As always, a good spotter can make the range a much more enjoyable place.
Change your "Drop..." to the elevation that you ended dialing to get your point of aim to match your point of impact. You will see the Kestrel calculate a new muzzle velocity. Exit out and be sure to accept your MV.
You are trued – easy day!
The next step is to look for targets that are half the distance of your truing distance. Confirm your data using shorter shots. And have fun! You saved a ton of ammo – now is the time to use it, when you have great data that is going to get you on to any target at any distance. Enjoy the smell of gunpowder, enjoy the sound of bullets hitting steel, and enjoy the process!