07-06-2011, 09:12 AM
I don't have strong views - any would do, they just have slightly different strengths and weaknesses.
If we were considering lead-cored bullets then I would definitely go for 6.5mm. With non-lead bullets it may be that a larger calibre is needed to get a reasonable weight. On the other hand, we don't want the weight to be too close to the 7.62mm or it won't be worth changing. So maybe 6.8mm would be the right compromise, but probably with a slightly bigger case and certainly with space for longer, more aerodynamic bullets than the 6.8 Rem. In fact, the late 1940s .270 British looks pretty close: 6.8mm calibre, case length 46mm, case diameter 11.2mm (.441). Pretty much the same as Cris Murray's 7x46 UIAC necked-down slightly.
If we were considering lead-cored bullets then I would definitely go for 6.5mm. With non-lead bullets it may be that a larger calibre is needed to get a reasonable weight. On the other hand, we don't want the weight to be too close to the 7.62mm or it won't be worth changing. So maybe 6.8mm would be the right compromise, but probably with a slightly bigger case and certainly with space for longer, more aerodynamic bullets than the 6.8 Rem. In fact, the late 1940s .270 British looks pretty close: 6.8mm calibre, case length 46mm, case diameter 11.2mm (.441). Pretty much the same as Cris Murray's 7x46 UIAC necked-down slightly.