September 27th, 2014

Mid-Sized Cartridge Comparison

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.

6mm Cartridge Comparison

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), and the same powders, particularly H4350, IMR 4007SSC, and N160 work well in the 6×47 SM, the 6XC, and the 6-6.5×47 Lapua. Alliant Reloder 17, slightly faster than H4350 but with a flatter (less “peaky”) burn curve, could also prove a good choice for both the 6XC and 6mm-6.5×47.

6XC vs. 6-6.5×47
Often the question is posed “Which is better, the 6XC or 6mm-6.5×47″. The correct answer seems to be “it depends”. Current batches of Norma-made 6XC brass are very good, while certain lots of 6.5×47 Lapua brass have somewhat disappointing neckwall uniformity, demanding neck-turning for best accuracy. Overall, however, the two cases (6mm-6.5×47 and 6XC) are nearly identical in performance. Some shooters believe the Lapua brass holds up better under full-power loads. On the other hand, Norma 6XC brass from is a bit less expensive than 6.5×47 brass.

The parent 6.5×47 Lapua case is rated at 63,090 psi, while the new CIP rating for the 6XC is 63,844 psi (4400 BAR). 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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