As long-range shooters, we tend to obsess over every little detail. After all, we’re trying to hit relatively small targets that are so far you may not even be able to see with the naked eye. While you might can get away with minor mistakes and still ring steel at short and medium ranges, as you extend the range those small mistakes or tiny inconsistencies are magnified. So, most things are important … but to differing degrees. This series of posts is taking a data-driven approach by using Applied Ballistic’s Weapon Employment Zone (WEZ) analysis tool to gain insight into how different field variables in real-world shooting affect the probability of hitting long-range targets.
I’ve played around with the WEZ tool a lot, and it was very enlightening! It challenged a lot of my long-held assumptions about how important different aspects were. As Bryan Litz said in his Accuracy & Precision for Long-Range Shooting book, “Looking at each variable separately teaches us how to assess the uncertainties of any shot and determine how critical each variable is to hitting the target.”
Previous posts looked at what impact we could expect from tightening our groups, lowering our muzzle velocity SD, or picking the ideal cartridge. In this post we’ll look at another element that we handloaders tend to fixate on:
How Much Does Muzzle Velocity Matter?
I have a friend named Bob, who’s a velocity addict. He is always running the latest hot-rod cartridge. To prove my point, his most recent rifle builds were a 300 Norma Magnum (launches a 230gr bullet up to 3000 fps) and a 6.5x280AI wildcat (launches a 140gr bullet at 3260 fps). I mean it wasn’t good enough to neck the 280 down to a 6.5 … he also Ackley Improved the case to get that last bit of velocity. It’s a wildcat of a wildcat! Do you have that friend? Are you that friend?! If we’re 100% honest, there is a little velocity fiend in each of us … me included.
Now it’s one thing to pick a hot-rod cartridge, but most of us who handload are tempted to push our cartridges to the limit … and a few may even go a little beyond recommended max loads (which I don’t condone). Whatever cartridge we’re using, we’re tempted to squeeze out just a few more feet per second to really get the most out of it.
Another way guys come at this is by running 26” or 28” barrels or even longer. Our example cartridge for most of these posts has been the popular 6.5 Creemdoor, and Berger Bullets Reloading manual says for that cartridge “Muzzle velocity will increase (or decrease) by approximately 25 fps per inch from a standard 24” barrel.” QuickLoad confirmed those estimates. So a lot of guys run those longer barrels, but a few shooter go with shorter 22” barrels … even though they know they are giving up some muzzle velocity to get there.
So what’s the benefit of pushing handloads to pick up those last few feet per second of muzzle velocity? Or, what are you giving up if you want to go with a shorter barrel?
I ran several simulations all with the same inputs for ballistics and uncertainties, but simply changing the muzzle velocities. This is all based on Applied Ballistics ballistics engine, so it should be very, very accurate. The muzzle velocities represent the low end of where I’ve seen 6.5 Creedmoor rifles with short 22” barrels firing the Hornady Factory 140gr A-Max Match Ammo through the upper end of what I’ve heard rumors of guys getting with the cartridge. I am NOT saying that you can or should try to run the 6.5 Creedmoor at the muzzle velocities displayed, but I’m simply trying to illustrate what the real benefit would be if you were to chase muzzle velocity to that point.
Notice the returns in this case appear mostly linear, although there are slightly decreasing returns with each step up in velocity. On average, you are increasing your hit percentage by 0.75% with each 25 fps increase in muzzle velocity. It’s not even a whole percentage point! Come on, that is so low it even surprised me.
As Bryan Litz reminds us in his book Accuracy & Precision for Long-Range Shooting: “Of course these results are specific to this bullet and cartridge, but are representative for this common class of weapon. The results of this average muzzle velocity analysis are clear. It is possible to increase hit percentage a noticeable amount by increasing barrel length and MV, but only if great increases are made.“
Honestly, if you’re having to push the max load of a cartridge to reach some target muzzle velocity … you’ve picked the wrong cartridge. As the last post clearly showed, there absolutely is a measurable benefit to picking a cartridge that is capable of higher much higher muzzle velocities. We live with an unprecedented abundance of cartridge choices. There are so many cartridges out there, that it is easy to find one to launch the exact bullet you want at the exact muzzle velocity you’re wanting … without pushing the limits of safe pressures. The 0.75% benefit of trying to eek out that last 25 fps out of a cartridge that isn’t intended to go that fast is just not worth the cost that could come with that. Start by picking the right cartridge that will give you the velocities you’re looking for below the max load, and then tune your load within that safe range of pressures.
One last point to keep in mind, is that all of this analysis assumes you have centered groups. That means they represent the best case scenario for hit percentage, since your odds only decrease if groups come off center. If you’re scope isn’t zeroed, or your rifle is canted slightly to one side, or your scope’s clicks aren’t calibrated correctly, or you pull the shot slightly … then your hit probability can decrease dramatically. But these simulations assume we have all that stuff squared away.
Other Posts In This Series
This post was one of a series of posts that takes a data-driven look at what impact different elements have on getting hits at long-range. Here are some others posts in this series:
- How Much Does Group Size Matter?
- How Much Does SD Matter?
- How Much Does Cartridge Matter?
- How Much Does Muzzle Velocity Matter?
- How Much Does Accurate Ranging Matter?
- How Much Does Wind Reading Matter?
- Overall Summary
If you want to dig more into this subject or explore some of these elements for your specific rifle, ammo, and ballistics, I’d encourage you to buy the Applied Ballistics Analytics Package to run these kinds of analysis yourself. You could also pick up Bryan’s Accuracy and Precision for Long-Range Shooting book, which has a ton of great info on these topics and other aspects of shooting.