Apologies if this is being posted to the wrong board, but this particular question falls into that sketchy middle ground between the big bore and pistol caliber venues.
I’ve always maintained an interest in the old MP/StG-44 round, and while this may be more sentimental than scientific given the history of the rifle for which it was developed, I’m intrigued by the fact that so many of the late-breaking AR calibers seem to be offering a near ballistic equivalence to the old Sturmgewehr catridge.
A quick overview of the basics reveals that the 7.92 kurz pushed a 107.3 grain bullet (assuming my conversion is correct) at roughly 2,250 fps. Without running a series of kinetic energy calculations – which I’m ill-equipped to do, anyway – it would appear that these figures are actually comparable to those reflected in the early 6.5/6.8 recipes.
With typical loadings, and 6.8 SPC numbers for reference, it would seem that we’ve returned to a place where we are again looking at launching 110-115 grain bullets at speeds in the 2,500 to 2,700 fps range. While this offers some real improvement over the 60+ year old 7.92 kurz (just as we would expect/hope), I find it rather instructive that the latest trends are really echoing the work the Germans did many, many decades ago.
Am I missing something, or is there a valid comparison to be made here?
I think it is a fairly good comparison between the two mostly because there are similar design parameters - trying to get that big cartridge performance out of a smaller package… Look at the “main” calibers of that era - .30-06, .303, 7.62x54R, and the German 7.92/8mm round was basically the same too… They wanted something smaller that would be good out to 300m or so but didn’t want to pay the weight, size ad recoil penalty of those bigger rounds.
From my reading, the 6.8 Rem SPC was looking for a similar goal going in the opposite direction - going from a round that was deemed by some to be too small and not powerful enough. And don’t forget the few other limiting variables thrown in - namely having to fit in the AR15/M16/M4 envelope.
I honestly don’t think the 6.8 Rem SPC was developed to be a modern mirror of the Kurz round but the goals involved and the limits forced upon the designers caused them to arrive at nearly the same round…
Just my $.02… All derived from reading about cartridges in books and on the errornet…