Rounds like the 6x47 Lapua share a lot of characteristics—not the least of which is low recoil that allows shooters to spot their shots at long range. (Photo submitted by the author)
August 13, 2024
By Frank Melloni
Affiliate Disclosure: This page contains affiliate links. We earn from qualifying purchases.
In the early days of precision shooting, it was widely believed that an accurate cartridge must sling a bullet of either .22 or .30 caliber. However, as time went on, we watched what were once considered benchmarks simply become bookends to a wide array of acceptable diameters.
As scientists and tinkerers started experimenting, several calibers started to show promise, with many surpassing the old standbys. Above most was 6mm, with handloaders citing bench-rest success with .243-inch bullets as far back as the early 1960s. Aside from their superior ballistics, most found them relatively easy to load for; hitting low standard deviations and extreme spreads took little to no effort.
Advertisement
Since the pioneer days, scores of 6mm cartridges have hit the scene, and there are probably more wildcat 6mms out there than standardized cartridges. Many are doing well in their unregulated state, and several have transcended to the commercial space, igniting their popularity.
(L.-r.): 6mm Norma BR, 6mm Dasher, 6XC, 6x47 Lapua, 6mm Creedmoor, 6 GT. All got their start as wildcats and have succeeded in capturing attention by varying degrees. (Photo submitted by the author) Here’s a look at six of them—their backgrounds and the traits that might help shooters decide on the one that best suits their needs.
1. The 6 BR Arguably, the 6 BR is the main one that cemented the .243-inch bullet into long-range acceptance. This stubby cartridge was among the first of its kind, and it was derived from another wildcat, the .308x1.5-inch Barnes—itself a cut-down .308 Win. The round was a prominent wildcat in the 1960s, and Remington eventually submitted the 6 BR for SAAMI acceptance and, by the late 80s, was chambering rifles and loading factory ammunition for its 6mm BR Rem.
Advertisement
However, as bullets change, so must everything else. In 1996, Norma introduced its loading and CIP-approved chamber specs. This lengthened cartridge utilizes bullets heavier than 70 grains, thus creating the 6 BR Norma and killing the Remington in the process.
Much confusion stems from this relationship, but if we liken it to the .223 Rem and 5.56 NATO relationship, it starts to make sense. The cases are similar: 1.560 inches in length, with a 30-degree shoulder. However, the chambers are different. The 6 BR Norma chamber is cut to accommodate the longer, heavier bullets; the 6 BR Rem. is not. Therefore a rifle chambered for 6 BR Rem. typically can’t accept 6 BR Norma ammo.
The Norma version, which has a case capacity of about 38 grains of water, can drive 115-grain bullets at speeds approaching 2,600 fps from a 26-inch barrel. The 30-degree shoulder angle headspaces the cartridge more consistently and keeps more of the powder burn contained inside of the case, saving the rifle’s throat.
Lapua offers amazing factory-loaded offerings with either its 90-grain or 105-grain Scenar-L bullet, fire-forming you excellent brass in the process. When it comes time to reload, Berger’s 105-grain Hybrid Target bullets are a perfect choice and pair well with Hodgdon Varget or Vihtavuori N-140. Overall, this cartridge excels inside of 700 yards, but most will agree there are better options for targets beyond that distance.
2. The 6mm Dasher The easiest way to picture the 6mm Dasher (r.) is to think of it as a 6mm BR with the shoulder pushed forward. (Photo submitted by the author) Enter one of the first “better” options. The 6mm Dasher is the brainchild of gunsmith Dan Dowling and his close friend and competitive shooter, Al Ashton. Its clever moniker is a mashup of their names with a less-than-subtle nod to its velocity increase over 6 BR.
Realizing the aforementioned cartridge’s potential and limitations, in 1999 Dowling and Asher drew up chamber specs that pushed its shoulder forward and sharpened it to 40 degrees. It picked up about 10 percent more case capacity in the process, now being able to hold approximately 41 grains of water. Pushing 115-grain bullets beyond 2,800 fps from a 26-inch barrel is child’s play for this cartridge, and most shooters will not notice an increase in recoil.
It was always easy to fire-form 6 Dasher brass from 6 BR brass, but today you can buy Dasher cases from Alpha Munitions or Peterson Cartridge—saving you the work of doing it yourself, not to mention barrel life. The 6 Dasher reloads well with Hodgdon Varget or Alliant’s Reloder-15.
Because it hasn’t been approved by either SAAMI or CIP, factory-loaded ammunition will be limited to boutique manufacturers. Eagle Eye Ammunition offers a few options, including one with the popular 110-grain Hornady A-Tip match bullet.
This cartridge excels at distances where 6 BR falls short, but at the cost of problematic feeding. While the 40-degree shoulder optimizes accuracy, it becomes less of a ramp and more of a brick wall when sliding off a magazine and into a chamber. Modified mags typically fix the problem, but some people curse this cartridge in anything other than a single-shot bench gun.
3. The 6XC The 6XC (r.) was made to improve the .243 Win. (l.) for competition. If you can’t find brass, you can make it from the .22-250 (c.), but it’s not easy. (Photo submitted by the author) I can only dream of a proficiency level where I outshoot all existing equipment and cartridges. David Tubb, on the other hand, achieved this dream shortly before 2003 when he started working on the 6XC. Short for “Across The Course,” this cartridge was built to solve the problem of using .243 Win. in an NRA High Power match.
The rifles used in this competition league typically feed from AR-10 or short-action Remington 700 magazines. Therefore, the .243 Win was perfect for the job, except the mag length limited it to shorter, lighter bullets that are more affected by wind.
Why not simply load heavier bullets? Tubb explained to me that the problem stems from the inside of the case, where the neck meets the shoulder. At this junction, there is an uncontrollable ledge of brass affectionally known as the “donut.” This intrusion contacts the bullet and adds additional tension at varying degrees—which changes velocity and affects accuracy, particularly at extended distances.
A better solution came when Tubb short-chambered a .243 rifle and reworked fire-formed .22-250 brass into what is now the 6XC. The finished case pushed the shoulder back significantly while sharpening the angle to 30 degrees. More brass was allocated to the neck, allowing long, high BC bullets to be seated without touching the donut, and the final case length came in at 1.902 inches.
Case capacity is around 49 grains of water, and out of a 24-inch barrel you can expect to crack the 3,000 fps mark even with heavy, 115-grain bullets. Few of us have the tenacity to go through what David did to make brass, but luckily, just a few years later, Norma CIP’d it, and we now have a few options for factory cases and even loaded ammunition.
Tubb’s company, Superior Shooting Systems, offers an excellent load built with Peterson brass and 115-grain DTAC bullets featuring a special cut that cleans up ballistic-coefficient deviation and further reduces vertical dispersion. He’s not shy about sharing the recipe, either. Simply load Hodgdon 4350 with those same DTACs and shoot it.
4. The 6x47 Lapua Shortly after Tubb finished his 6XC, Lapua came out with its smash-hit 6.5x47 cartridge. It didn’t take long for wildcatters to neck it down and call the modified case the 6x47 Lapua. The case retains the original’s 30-degree shoulder angle, measures 1.850 inches and holds about 45 grains of water. It can push 115-grain bullets up to about 2,900 fps from a 24-inch barrel.
Initially seen as a rival to the 6XC because the Lapua brass is easier to come by, the cartridge quickly faded after Tubb’s round was standardized. You are going to be hard-pressed to find factory ammunition, rifles and perhaps even pre-necked brass.
Berger’s 108-grain boattail target bullets are a favorite among competitors running 6x47 and typically do well with IMR 4350 or Reloder 15. This creates a top-performing round at distances in excess of 1,000 yards and is a touch lighter on the shoulder than 6XC. The downside is reported finickiness and more time in load development.
5. The 6mm Creedmoor The 6mm Creedmoor (r.) can be made by necking down a 6.5 Creedmoor case, but there are plenty of options for sized cases and factory ammo. (Photo submitted by the author) Calling this cartridge “obscure” is a bit of a stretch. After all, you can walk into just about any big-box gun store and likely find both ammo and rifle without much trouble. However, it’s pertinent to this discussion because, like the others, it started as a wildcat.
In 2009, gun writer John B. Snow was looking to write about what it takes to build a wildcat cartridge. Wanting a flat-shooting round for Western medium game by the end of the project, he thought about pushing today’s high-BC 6mm bullets faster.
He selected the popular 6.5 Creedmoor case as a starting point and worked with Hornady’s Joe Thielen to create the 6mm HOLE cartridge, which was short for Hornady Outdoor Life Express. However, if John wanted to see the company mass-produce brass, he was going to have to settle for the new round being called 6mm Creedmoor.
As fate would have it, Precision Rifle Series (PRS) shooting had just ramped up, and many competitors were hitting the same roadblocks as David Tubb with the .243 Win. Originally intended to be a hunting round, the 6mm Creedmoor was an instant and unintentional success in this field as PRS and National Rifle League competitors flocked to it.
Due to this interest, the team filed for SAAMI approval, and the cartridge was standardized in 2017. Today nearly every major manufacturer makes at least one factory load. Re-creating Hornady’s 108-grain ELD Match load is a cinch, and I’ve found excellent results using Winchester StaBall 6.5.
The 6 Creedmoor has a lot going for it, but I caution its use in applications where barrel heat is a concern. Most of the rifles I’ve tested it in warm up within 15 shots, which will slow down a varmint hunt or a sunny practice session.
6. The 6 GT Just as Tubb built his round for his preferred style of competition, George Gardner of GA Precision and Tom Jacobs of Vapor Trail Bullets did the same with the 6 GT. In PRS/NRL shooting, the ability to spot your shots is crucial, and this makes recoil a larger factor than it is in NRA High Power. Additionally, smooth feeding is critical, as the entire match can be considered rapid fire, not just certain portions like in the NRA competition.
Above all, the 6 GT is built to cycle, and some might even consider it a better 6 Dasher. With a 35-degree shoulder angle, it gains Ackley-ish improvement without being so steep it impedes feeding. At 1.725 inches, the case is 0.175 inch longer than the Dasher, which places the tip of the bullet into the chamber before the feed lips let go of the case—ensuring it remains under control until it gets where it needs to go.
Approved by SAAMI in 2022, a standard case will hold 43 grains of water and is capable of pushing a 115-grain bullet to well over 2,900 fps. Given its smaller stature, this makes it one of the more efficient cartridges of the bunch.
GA Precision sells ammo—loaded under exclusive contract by Hornady, a 109-grain ELD-Match. Eagle Eye loads that bullet, too, along with Berger’s 105-grain Hybrid and Hornady 110-grain A-Tip. GA also sells brass. This cartridge was built to run on Hodgdon Varget, so give it what it wants, and it won’t let you down.
It’s hard to find a limitation for this round, as it was built specifically to address the issues left behind by its predecessors. With the exception of extreme distance shooting, I’d say its only flaw is the limited ammo and component availability, but this is already starting to see resolution.
Honorable Mention 6 ARC While it didn’t get its start as a wildcat cartridge, we can’t leave without mentioning the 6mm ARC. Developed by Hornady for special military units, the 6mm ARC is a necked-down 6.5 Grendel case with the neck/shoulder junction pushed closer to the case head, allowing the use of high-BC Very Low Drag (VLD) bullets while still fitting in an AR-15 or short-action bolt gun.
Hornady’s 108-grain ELD-Match load generates 2,750 fps at the muzzle from a 24-inch barrel, and it’s still supersonic between 1,200 and 1,300 yards. Offerings for hunters currently include a 103-grain ELD-X Precision Hunter at 2,800 fps for thin-skinned big game, as well as the company’s new VT (Varmint Target)—an 80-grain V-Match bullet at 3,020 fps. There’s also a defense- or plinking-minded 105-grain boattail hollowpoint at 2,750 fps. Rifles are available from various boutique makers, as well as Howa, Mossberg, Savage and Stag Arms.
The world of 6mm can be intense and a little scary since most of the cartridge names give little information as to where they land in the spectrum. I hope this article helped to shed a little light into them and helped you make your decision on your next build. If you time it right, maybe you’ll get two years out of it before the next latest and greatest 6mm cartridge comes along.
