Mid-Sized 6mm Cartridges — Great Accuracy & More Zip than 6BR
Many precision-oriented shooters are discovering that the “middle ground” in cartridge size is optimal for the 100gr to 115gr match bullets. With a mid-sized cartridge, you can run these pills faster than a 6BR or Dasher, without giving up much, if any, accuracy to a 6BR or BR Improved. The most accurate 600-yard rifle at this Editor’s local club is a 6-6.5×47. It can shoot as tight as a 6BR past 300 yards, plus it offers better ballistics, pushing 105 Bergers at 3140 fps.
If you’re considering a mid-sized 6mm cartridge for your next rifle, you’re probably wondering WHICH mid-size 6mm cartridge is best. We are often asked “what’s the difference between the 6×47 Swiss Match, the 6XC, and the 6.5×47 Lapua necked down to 6mm?” All three cartridges have 30° shoulders and fit a .308-sized boltface. However, alone among the three, the 6mm-6.5×47 has a small primer pocket and small flash hole. The 6×47 Swiss Match (made by RUAG), and the 6XC (produced by Norma), have a large primer pocket and large flash hole, just like a .308 Winchester.
Forum member DesertLefty has provided a line-up photo, with 6mmBR and .260 Rem cases provided for comparison. As you can see, the three mid-sized cases (6x47SM, 6.5×47 Lapua, and 6XC) are very similar. The Swiss Match has the longest neck, while the 6XC enjoys the highest capacity. But performance is very similar among the three cartridges (with the 6.5×47 necked down to 6mm). The same powders, (particularly H4350, Reloder 17, and IMR 4007SSC) work well in the 6×47 SM, the 6XC, and the 6-6.5×47 Lapua. The parent 6.5×47 Lapua case is rated at 63090 psi, while the new CIP rating for the 6XC is 63844 psi (4400 BAR). Both the necked-down Lapua brass and the Norma-brand 6XC brass can hold stout loads. Though the 6mm-6.5×47 has slightly less powder capacity than the 6XC, max velocities with 105-108gr bullets are quite similar. However, you should not substitute loads from the 6XC directly to the 6mm-6.5×47 or vice-versa. Because of the different case capacities and primer sizes, you should work up loads separately for each cartridge.
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Tags: 6-6.5x47, 6XC, Lapua, Swiss Match, Tubb
Hey I can get 3100 fps with the Berger 105VLD out of my 6mm HAGAR spacegun too! ‘Course I can’t reload that case again, but it shoots awesome out to 600 yards even at 2,900 fps.
Speed ain’t the only measure of success punching paper! Gonna try it at 1K later next month, just for giggles.
Why not just use a boring old 243? At least you can find rifles chambered for it.
The importance of the small primer in this size case can be overstated. The important thing is to have a mild primer flash and that can be accomplished with the Russian (Wolf) primers. One thing that shouldn’t be overlooked is that the 6x47SM is not available in the US and the 6-6.5×47 is a wildcat and standardization of dimensions for reamers and dies is not guaranteed. I’ve considered all three but went with the 6XC for my 1000 yard cartridge based on performance, standardization and good brass availability. Only the 6XC gives you all those factors.
My experience of over three years shooting the 6XC (2,421 rounds)from 300 to 900 metres using Sierra 107 gr projectiles and Reloader 15 powder is that it will more than hold its own against the 6.5 mm, 7 mm and .30 calibre catridges up to 900 meters (and maybe beyond). Wind reading skills may require slightly more attention on an F-Class Open target but that is more than made up for by superior consistent elevation and lack of recoil over the larger calibres. Accuracy with the 6XC is not an issue. I have retired the 6.5/257 AI in favour of the 6XC at all ranges.
I think the 6mmBRX and 6mmDasher have spoken for themself with the records they have broken. They exhibit accuracy, ecconomy, reliability and are just fun to shoot. They fill the nitch of just enough power to be better than the old stand by 6mmBR.
Nat Lambeth
I built a Savage rifle chambered for the .243 Winchester held short by 1/4″, very similar to the three cartridges discussed. My intent was simply to make a cartridge that would use less powder than the .308, kick less and have reasonable barrel life. I use the 6.5×47 Lapua as the parent case.
The first time out it shot a one-hole group at 100yd barely bigger than bullet diameter. On the two occasions that I have shot it at 1,000yd (87gr V-Max) I have shot a 4″ group and can consistently hit clay pigeons. This performance from a couple of Adams and Bennet barrels from Midway. BTW, I only shoot that rifle from a bipod.
To say that these cartridges are inherently accurate is a gross understatement. A lot of fun to shoot, too.
I’ve often thought the 6.5 Creedmoor necked down to 6MM would make a good cartridge but the 6XC appears to be about the same thing. If I ever get around to building a 6MM I’ll probably go with the 6XC instead.
Do those primers look flattened to anyone else?
Why was the 6.5 Creedmore not in the mix?
@German Salazar what kind of “real world” barrel life are you getting from your 6XC? Bah humbug on the overbore calculators. I think real world numbers from an actual competitive shooter like yourself are of far more value.
Another cartridge worth considering is the new 6 mm Super. This case is nothing more than a long necked .243 with a 30 degree shoulder. As .243 cases are easy to obtain and only require reshaping through a 6 mm Super die before they are ready for use. Also starting loads, especially for 105 gr to 107 gr projectiles can be readily obtained from .243 loading data supplied by most loading manuals. Early experiments with 105 grain to 115 grain projectiles show very promising results. Testing with RL 15 and RL 17 indicates that the case has all the attributes of the 6XC, 6 mm Swiss Match etc., without the case stretching and “blow torch” effect that the short neck of the .243 has on the lands. The 6 mm Super seems to be able to comfortably propel 115 grain projectiles out of 28/30 inch barrels at around 3,000 fps with reasonable pressures. More testing is required, but the results look promising.
@Jed – from my experience the 6XC barrel should be good for about 2,500 rounds before rechambering and recrowning should be considered. My first 6XC barrel with the above maintenance has now seen close to 4,000 rounds and is still competitive for F-Class open. All this of course depends on the operational practices and maintenance one employs during the life of the barrel. Time will tell how well my second barrel will perform.
What is old is new again. Elgin Gates’s 6.5 IHMSA is back!
I still am partial to the 7mm version tho…
I have played extensively witht he 6-6.5X47L and it was a dog. I tried 8, 7.5 and 7 twist barrels. This cartridge would only produce reasonable accuracy at velocities no different than a 6BR for the 105 VLD’s and would never shoot the 115’s with anything better than an inconsistent .5MOA accuracy.
I tried using trimmed 6XC brass and there was a slight improvement, so I think the small flash hole may have some detrimental effects.
The 6XC is king of the 115 grain hill as far as I am concerned, and for 105’s I will simply stick with the unbeatable 6BR…
1. Creedmore is coming out with the 6mm Creedmore this year.
2. Several of these 6mm discussed will excell in the velocity department but also excell in the barrel erotion department. The XC only gets about 100 more rounds of barrel life than a .243 Winchester. keeping velocities at 3050 fps and powders quantities below 34 grains is important.
Nat Lambeth
Curious as to why the 6mm International isn’t a huge player today. Seems like David Tubb and the 6XC went all the way around Robin Hood’s barn to achieve what Mike Walkers 6mm international achieved decades ago from the exact same parent 250 case no less.
http://stevespages.com/jpg/cd6international.jpg
Jed- I agree 100%!
What’s different [with these new arrivals] than the 6/250; 6/250 Ack. Imp.; or, the original 6 HLS??
Or, as Jed states, the OLDER yet 6mm Intn’l! 
When it comes to smokeless powder cases, there really isn’t much truly NEW – just more/better powder selection(s) . . . RG