Will 6mm Br Norma Feed Properly Through a Short Action

Welcome to "What The Pros Use" 2018 Edition! I recently surveyed the top ranked shooters in both the Precision Rifle Series (PRS) and the National Rifle League (NRL) to learn what gear they're running in long range rifle matches. These guys represent the best precision rifle shooters in the country, and over the next several posts I'll be publishing the results. Learn more about the PRS & NRL.

Most Popular Rifle Caliber

I can remember a time when there was a battle between which caliber was most popular: 6mm or 6.5mm? That battle appears to be decisively won at this point, because 6mm bullets clearly dominate precision rifle competitions. 7 out of 8 of these top shooters use a 6mm cartridge.

On the chart above, the various colors represent where a shooter landed in terms of rank. For example, black indicates shooters who finished in the top 10 in the PRS, the darkest blue is people who finished 11-25 in the PRS, and the lighter the blue, the further out they finished in overall standings. The green colors represents the top shooters in the NRL, where the darkest green is the top 10, medium green is 11-25, and light green are the shooters who's season rank landed from 26th to 50th. The chart legend itemizes the league and ranks each color represents, but basically the darker the color, the higher up the shooters placed.

While the 6mm dominates the chart above, there are a couple of things worth noting:

1. At least one of the top 10 guys in each league said they used a 6.5mm, so rest assured a good shooter can still be competitive with them.
2. Two guys in the NRL's top 50 said they were using a 22 caliber, and that's the first year that's popped up among top shooters.

The NRL rules allow a rifle of "any caliber between .224 to .308 and not to exceed 3,200 fps." The PRS has similar rules but doesn't limit caliber on the smaller end. However, I'll admit that I was a bit surprised to see guys using 22 calibers at this level. Shows what I know! 😉

The trend seems to be going to smaller calibers and smaller cases. The reduced recoil helps shooters better spot shots when shooting from improvised positions off barricades. Something helping this trend is the growing use of target hit indicators, like those made by MagnetoSpeed. Those are now common at most major rifle matches on targets 1,000 yards and beyond. That means you don't have to rock the target to get the "IMPACT!" call from the RO. In the past, more guys were using 6.5mm bullets because there is nothing more frustrating than actually getting a round on target but not getting a call for it. So terminal energy was an important consideration, but the more widespread use of target hit indicators has decreased the need for more energy on the target and allows us all to use lighter bullets at lower speeds.

Most Popular Rifle Cartridges

When we dive into the specific cartridges guys were running, there has been a significant shift over the past couple years. The 6mm Dasher (aka 6 Dasher) has become a fan favorite – by a fairly wide margin.

The 6mm Dasher has been widely adopted among top shooters, but the 6mm Creedmoor is still a favorite as well. In fact, it takes the next 3 cartridges combined to equal as many people as those shooting the 6mm Dasher or 6mm Creedmoor. Almost half of the top shooters are using one of those two cartridges, at 47.4%.

The 6XC was still represented in good numbers. The Creedmoor and "x47 Lapua" case designs are both very similar to the 6XC cartridge.

Then you have a group of cases: 6mm BRA, 6mm BRX, and 6mm BR. Those, along with the 6mm Dasher, 6mm Comet, and 22 BR are all variants of the 6BR case. You can see a nice side-by-side photo of the 6mm BRA and 6mm Dasher below (photo courtesy of Wheeler Accuracy, shared with permission). I'll dive into all of these 6 Dasher and 6mm BR cartridges in more detail towards the end of this post.

The good old 6.5×47 Lapua and 6.5 Creedmoor are still represented in significant numbers. I realize a lot of guys reading this who own a rifle chambered in one of those. Please don't feel like you should trade it in for one of these new, shiny cartridges. Those cartridges are still capable of top-tier performance. I personally recommend the 6.5 Creedmoor to more of my family and friends than any other cartridge. Remember that looking at what gear these guys are running is fun, but don't let it steal your joy or contentment of using what you already own.

On the survey I asked these top shooters, "If you could give a new shooter one piece of advice, what would it be?" Here is some timely wisdom from a well-respected veteran on this topic in particular:

"Start with good gear, then focus on yourself in learning and improving your fundamentals.  Don't chase equipment, speed, new cartridges, etc." – Wade Stuteville, 2012 PRS Champion & perennial top 100 competitor, and owner/gunsmith of Stuteville Precision, partner in Impact Precision Shooting.

Of the guys in the NRL using a 22 caliber, both were using the 22 BR. One finished 20th and the other was 39th overall for the season in the NRL, so that cartridge can be competitive with a good shooter behind it.

Lastly, one of the top shooters was using a 7mm, which was the 7MMachine. It was launching the 150gr ELD-X at 2,810 fps. I asked the shooter, Matt Neitzke, about it and he said, "The 7MMachine is nothing too special. Just a 30 degree 7mm-08. I love this cartridge though. It routinely out scores my 6XC."

Now let's take a closer look at the cartridges among the top 10 shooters in each league:

The story in the chart above echoes similar trends to the wider group, except the 6mm Dasher is even more dominant among the best of the best shooters! 40% of those ranked in the top 10 in either league were running a 6mm Dasher. That's crazy, considering only 6 of the top 100 in the PRS were using the Dasher when surveyed two years ago. It's pretty clear that the best precision rifle shooters in the country put their money on the 6mm Dasher when it comes to long-range shooting.

How Much Does Cartridge Matter?As long-range shooters, we tend to obsess over every little detail. This post uses Applied Ballistic's Weapon Employment Zone (WEZ) analysis tool to gain data-driven insight into how different field variables in real-world shooting affect the probability of hitting long-range targets. Learn how much hit % changes based on which cartridge you're shooting.

Rise of the 6mm Dasher & Other 6BR Cases

48% of all the shooters surveyed were using a cartridge based on the 6mm BR case. That was even higher at 65% among those who finished in the top 10 in either league!

Here is a look at the most popular variants these shooters were using that were based on the 6mm BR. Each has small tweaks that adds a little case capacity to the 6mm Norma BR case. However, if you held these cases in your hand it might be hard to tell them apart without close inspection.

Norma has released brass for the 6mm Dasher, so that you don't have to wildcat it from Lapua's 6mm BR brass if you don't want to. The Norma version of the 6mm Dasher features a slightly longer neck too. But of all the 47 shooters who said they run the 6mm Dasher, only one of those said they were using Norma brass – 46 of 47 said they were using Lapua brass. Some shooters say Norma made the 6mm Dasher brass too thick, which made it have slightly less powder capacity and the muzzle velocities you could achieve were around 100 fps less than if you'd used Lapua brass.

t could be that the Norma brass may just not be as readily available, or these guys may just prefer to do the extra steps of wildcatting for the quality of Lapua's brass.

The 6mm Comet and 22 BR are other cartridges a couple of these guys were using that are based off the 6mm BR. I couldn't find a lot of info on the 6mm Comet, but it sounds similar to the Dasher. The 22 BR is obviously a 6BR necked down to 22 caliber.

Until recently, the overwhelming majority of shooters were using cases like the Creedmoor, "x47 Lapua," and 6XC, which all have a case capacity very close to 50 grains of H2O. The 6mm BR cases represent a significant departure to cases with a 40 grain capacity of H2O. That's a 20% reduction in case volume between a Creedmoor-class case and a BR-class case!

This decrease in capacity means you're burning less powder per shot, which should extend barrel life. I'm sure that is appreciated since 65% of these guys shoot 4,000 rounds or more each year! But it's not like there is a 20% decrease in velocity or energy at the muzzle. In fact, based on the muzzle velocities these shooters said they were running, there is only a 4-5% decrease in muzzle velocity from the 6mm Creedmoor to the 6mm Dasher, so these cartridges are simply "more efficient."

I asked each shooter what bullet and muzzle velocity they were running, and did some analysis on that. Here is the typical muzzle velocity the shooters were running in the top 6mm cartridges. (Note: Most these guys run a 26″ barrel.)

One last interesting point is that I asked each shooter what their standard deviation (SD) was for their muzzle velocity. If you've never heard of that, we often reference SD as a gauge for the consistency of your muzzle velocity shot-to-shot. If you have a small SD like 4 fps, it means that most of your shots are very close to your average muzzle velocity. A larger SD (like 15 fps) would indicate that your muzzle velocity varies pretty significantly from your average, which means you'd expect to see more vertical spread in your impacts at long range. We all want really low SD's, and many of us fixate on getting that number as low as possible. Some cartridge designs make achieving a low SD easier than others, and while it certainly isn't totally driven by case design, I thought it'd be interesting to look at what SD's these guys were getting on average based on the cartridge they were running.

The chart above shows one more reason so many guys are loving cartridges based on the 6BR – all of them have an average SD that is around 5 or less! Keep in mind that this based on what the shooters themselves said their SD was, but it was averaged over a relatively large group. The 6.5 Creedmoor data is only based on 5 shooters that said they handload and use that cartridge, but all the other data is based on responses from 9 or more of these top shooters. I don't want to over-simplify this, but that's a pretty interesting result from this unique sample size.

For more details on these newer cartridges, check out these links:

• 6mm BRA
• 6mm BRX
• 6mm Dasher (Good review on new 6mm Dasher brass from Norma)

Stay Tuned!

Stay tuned for more posts in this "What The Pros Use" series in the near future, as I cover other equipment these top shooters said they're currently running. At least one of those posts will dive deeper in the reloading components, and it will share a little more related to cartridges including the specific loads these guys are running.

This is one of several posts based on a gear survey of the top PRS shooters. Want to be the first to know when the next set of results is posted? Sign-up to receive new posts via email.

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Source: https://precisionrifleblog.com/2018/12/14/rifle-caliber/

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