Sure - I actually wrote a bit on this last fall which I'll share here. In hindsight, I kind of regret including the top and bottom cartridges in the photo below which really don't fit in the line up - the 6 ARC at the bottom and the 243win at the top, but they're relatively familiar to a lot of folks, AND, both represent the outer bound of "too little" and "too much," so at the time, it seemed pertinent to include them.
I want to first shape this discussion a little by talking about what is popular, why, and how folks can make these decisions:
1) Affirming here - shooting anything but a 6mm in PRS competition is self-limiting. Some guys play with 22 GT's and Creeds, some have played with 25 Creeds, and the 6.5 Creed still hangs on, especially with new shooters, but the 22's have less target response and less splash, making them harder to spot, and the 25's and 6.5's need more horsepower and deliver more recoil, also making them more difficult to self-spot, so the 6mm's are firmly defending the "sweet spot" for PRS competition. Any other choice has consequences.
2) 6 BR based cartridges are BY FAR the most popular cartridges used in the PRS. The 6 CREED has often been the most popular single cartridge at the PRS finale any given year, but calibrating this, that can be due to location of the match, and the fact there are multiple BR based cartridges and only one Creedmoor version.
2) Acknowledging again why --> PRS is a game of recoil management. We shoot from compromised positions with the pressures of time and movement, but we have to be able to SEE our shots, either impact/target responses or miss splashes. We're also shooting long range, with the average distance fired at most PRS matches somewhere between 600-800 yards. Bigger cases will shoot flatter, which makes targets wider in the wind, BUT, it also means the rifle pushes the shooter farther off of target, potentially losing critical information from our shots which could be used to deliver the next shot on target. So some shooters may keep multiple rifles to suit different matches: For example, I have a rifle in 6 Creed and another in 6 Dasher, I'll shoot my Dasher for the Punisher Positional in July where ranges are all under 1,000yrds and there is NO traditional prone on any stages, whereas I'll shoot my 6 Creed at King of Coal Canyon in New Mexico next month since it's predominantly prone focused and has longer range opportunities.
3) Most PRS shooters reload, but compared to say, F-class or Benchrest, there are far more PRS shooters using factory ammo than these other match formats. So some shooters might choose a cartridge based on factory ammo availability. For example, in 2018/2019 when Robert Brantley (PRS Pro shooter, King of 2 Mile winner and placer, and worldwide hero to kittens) decided to focus more on ELR than PRS, he rebarreled his rifle to 6.5 Creed and shot factory ammo all season. This limits options considerably - the 6 Creed and 6 GT, or buying boutique ammo for Dasher or BRA from places like Clay's Cartridge Company.
5) In the photo below, cut the 6 ARC off of the bottom and 243win off of the top, and pick one of the rounds in between, and you won't be "wrong". Personally, I'd only choose 6 BRA, Dasher, GT, or Creed, and I DO shoot the 6 Dasher and Creed for PRS (my son is dead set on shooting a GT).
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6 ARC – The ARC shouldn't really be here, but it's becoming familiar to some folks, AND within its division of PRS, it's the best option. It's slightly longer than the BR, but a smaller diameter, so a little less case capacity overall. There are typically only one, two, or three competitors in Gas Gun at any given 2 day Pro Series match - and usually those guys are shooting large frame AR's in 6 GT or Creed, or guys are shooting 5.56 or 308, BUT if a guy were shooting Gas Gun division and didn't want a large frame AR, the ARC is far and away the best choice. A 24" barreled gas gun will get 108 class bullets up to about 2700fps, which makes targets pretty narrow at long range (extra wind drift). In a Bolt Action rifle with a bit more barrel and more pressure, it can get up over 2900fps. But the ARC is pushing hard to do this, whereas a 6 BR can do the same with less pressure, or do more at the same pressure. Personally, I weigh two problems for 6 ARC in a bolt gun for PRS - 1) it uses an uncommon .440" boltface, which makes changing cartridge more expensive in the future, and 2) it's kind of a Beast with No Nation when it comes to powder selection. It's a bit too small for H4895, and typically, the best performance is found from Leverevolution, which is highly temperature sensitive. So 6 ARC is the best option for a small frame Gas Gun Division rifle, but a small frame Gas Gun is a worse idea than a large frame, and Gas Gun Division is a worse idea than Open, TAC, or Production with a bolt gun, and in a bolt gun, eh...
6 BR – The 6 BR and its descendants have made up about half of the field at the Precision Rifle Series Finale, but there are too many BR based variants for any one of them to make up the single-most-popular round in the game. With the BR as the parent case, shorter than the rest with lower capacity, it’s also the slowest. The BR will push a 105/108 class bullet up around 2800fps without pushing pressures. Stupid simple to load, stupid accurate. H4895's up to Varget. Straight BR's tend to be less popular than the improved variants, for the extra speed they bring to the table, but straight BR used to be more popular in the East.
6 BRA – the BRA retains the neck of the BR in the same position, and is a true Ackley Improved form, only blowing out the shoulder to a steeper angle. This adds just enough capacity to pick up a hair under 100 fps over the parent, but also helps reduce trimming. A lot of guys are finding H4895 to be the magic dust for BRA, but Varget performs exceptionally well here also. BRA is very popular among the crew of shooters I run with in Kansas and Oklahoma, and good quality brass is available with no fireforming from Alpha.
6 Dasher – the Dasher not only blows the shoulder to a steeper angle, but also blows it forward, picking up even greater case capacity, and greater speed. At maximum pressure, Dashers can knock on the door of 3000fps with some 105/108 class bullets, but typically around 2950 keeps things behaving well (I personally run mine around 2850 with a very mild load). Varget is the King of the Dasher, while some guys do use H4350 or H4895 - but personally, I think the BRA is really maxing out the case for H4895, and the Dasher's slight increase in capacity puts it firmly center in the "sweet spot" of Varget. A lot of us still make Dasher brass from Lapua 6 BR, but Alpha and Peterson make Dasher brass.
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Other BR Based Cartridges: Lumping these guys together here, there are cartridges like 6 BRX, BRDX, BRI, etc which are different twists on this or that between the BR and Dasher (if memory serves BRDX is actually blown forward farther than the Dasher, but is very similar).
6 GT – The new kid on the block, designed by George Gardner and Tom Jacobs (G & T). These guys designed the GT case to get the most speed as they could from Varget with 105-110 class 6mm bullets, without needed to step to a slower powder like H4350. Great barrel life, and exceptional efficiency – the GT pushes through 3000fps with mild pressures while still using low 30-something grain charge weights and holding stable for 2500-3000 rounds. The GT is SAAMI standardized, so unlike the BR based cases, and most of the rest of this list, the GT is available as factory ammo, and even factory rifles. Personally, I think frequently that if I were starting over, maybe I wouldn't use 6 Creeds at all because the barrel life is so much better with the GT. George & Tom designed it to be "as big as it can be to still use Varget," so some shooters find it falling off of the edge of Varget and prefer H4350 for GT.
6x47L – a necked down 6.5x47L, this wildcat has a niche following. The x47 will exceed the performance of the smaller cases, pushing up in the 3050-3100fps ballpark without riding the pressure limit, and the rest of this list of larger cases do start eating barrels faster than some folks would prefer – certainly faster than the previously discussed smaller cases. I know a lot of Dasher and Creed shooters which report the x47L as finicky, but in the only loading I did for it, it was just another option to 6 creed, not really a worse or better option.
6 XC (XCII) – Developed by David Tubb for Cross the Course Highpower matches (hence “XC”) the 6 XC has earned a loyal niche following of PRS shooters. Originally, the 6 XC was a 22-250 based wildcat, but Norma started making brass - which created a unique situation where tight chambers meant for fireformed 22-250 brass would eventually get sticky after a couple of firings with fatter Norma factory brass, so the XC II chamber came about - leaving a little more room at the base to eliminate that click after cases grow with firing. Kestrel & Magnetospeed Pro Shooter Ryan Hey swears by 6XC, which might both demonstrate it's a good round, but also that it takes a wild streak to choose it.
6 Creed – The son of the 6.5 Creedmoor, this is another SAAMI standardized cartridge on our list. The Creed case is on the cusp of “too large” for PRS use – it can and does push these 105-110 class bullets right up against the 3200fps speed limit enforced at PRS matches to protect range steel, and eats barrels in half of the time of the BR based cartridges. However, the 6 Creed has been the most popular single cartridges used in the last handful of PRS finales by world leading shooters, making up somewhere around ¼ to 1/3 of the field at the Finale. H4350 is the easy button here, but when barrels are toast by 1400 rounds, a 6 Creed shooter can never get too comfortable. 6 Creed also has the luxury, or curse, depending upon how you view it, of having brass available both in large and small rifle primers. Shooting my 6 Creed during matches typically feels smart - my targets are "wider" than most of the rest of the field, but afterwards, when I dump brass after a match, I think about my barrel round count and I feel a little bit like I'm pulling single-use tires off of a Drag Racer... Every match is 10-20% of my barrel life, and it really sucks to say that out loud.
243 Win – We're slipping off of the edge of "too big" with the 243win. It takes a little consideration to fit long ogive, high BC, heavy 6mm bullets into mag length with 243win, and we typically have to use custom throats and obviously fast twist barrels... None of which are actually problems, because it all works and is all known science - BUT... The 243win has too much case capacity for PRS, and will easily exceed the 3200fps maximum muzzle velocity "speed limit" of the PRS with most of the bullets we use in the barrel lengths we use them (predominantly for forward balance). AND... the 243win is a little more finnicky to load, and has more case growth due to its taper and sloping shoulder, AND we only have one option for small primer brass, which is to form brass from Lapua Palma... AND we're still living at the very top of the recoil threshold for the sport, AND we're eating barrels in ~900 rounds. I shot 243win and AI for over 2 dozen barrels before I started shooting PRS, 750-1000rnds was all I'd get from barrels. Everything I did with 243win and 243 AI was aimed at making it do what we do now with the 6 Creed, so I won't likely revisit the 243win again. Pro Shooter Todd Williams has shot most of his career with 243wins, and made it to the Finale multiple times with it, even in the last couple of years.
