In this week’s blog I’m going to hack up the idea of bullet selection, so bear with me.
I know, this topic is like opening Pandora’s Box. At the bottom of that box is one conclusive commonality – accurately putting rounds on target, paper or pump station.
As can be seen in our pet load chart, there are several bullet choices that seem to shoot very well out of the 7mm Valkyrie AR with various barrel lengths. Everything from the 120gr Barnes TTSX to the 168gr Berger VLD Hunting, so, which one should you choose?
That choice isn’t really any easier than selecting a caliber or rifle, Remington, Ruger, Winchester or Wetherby. Lucky for you, it’s a good thing you’ve already made that decision in the AR-15 platform and the Valkyrie. Now, why choose one bullet over another?
Let’s start by considering what will be catching your bullet.
Shooting into an inanimate backstop with no requirement for rapid fire leans towards a longer bullet with a higher BC to achieve bug holes at extended ranges. This choice should be an easier one with limited options of Berger, Nosler and a few other boutique brands.
Choosing one for taking game involves some additional consideration. The most significant factors, for me, are expected ranges and quarry. These two factors play into the most important, first choice – bullet weight.
Even if you have the most accurate load that never misses (so long as you do your part) it is not ethically effective if it does not retain enough energy to cause terminal damage at your expected ranges. Bottom line, fast and flat isn’t always the best choice. An elk or deer isn’t exactly a prairie dog.
With that being said, by using various ballistics software, it’s possible to at least choose a range of bullet weights that will deliver energy on your target at range. Now that you’ve narrowed down the herd you can work up a load from those bullets in the weight range selected.
Sounds simple, right? Sometimes having too many choices, as can be the case with this caliber since it shoots so many of them well, isn’t necessarily a bad thing. Pick a few that are available to you, and a couple of powders (more on that later) and start shooting.
One of the things that makes 7mm so effective is the balance between bullet diameter, bullet length, and sectional density when compared to similar calibers like 6.5 and .30. When you're working with a finite magazine length, bullet length in relation to weight is a huge factor because that impacts on powder capacity in the case.
6.5 and smaller diameter calibers have long bullets in relation to their weight, making it hard to find powders that have enough load density to achieve good velocity with medium game suitable bullets. .30 caliber has density problems at typical game bullet weights in AR length rounds. You can't get enough powder in the case to get good velocity due to the heavy weight.
In 7mm you have sufficient diameter to get good weight without excessive bullet length, eliminating 6.5 and smaller for medium and large game. In turn, those weights have good sectional density, so you get good ranging and penetration with less recoil compared to an equivalent .30 caliber bullet.
A 140 gr. 7mm is heavier than any of the smaller caliber rounds, but still light enough to achieve high velocity, and is about equal to a 165 gr. in .30 cal. A 160 gr. 7mm in the 7 VAR, 7mm-08, 7x57, etc. gives energy and penetration that you need to go to 190 gr. in .30 cal. to achieve.
So, 7mm sits firmly astride the middle ground and is good at both ends of the spectrum. That's why so many of the bullets available in 7mm do so well, and it isn't hard to get good results by just matching the bullet weight to the intended use. For the Valkyrie the best all around choice is one of the 140 gr. class of bullet. Find the one your rifle likes best and you're good to go.