Assault rifles and their ammunition

[stanc]

Yikes, that chart on p. 29 seems to make a pretty good argument for the 5.56 cartridge. If you figure the Grendel weight as similar to a 7.62x39 round then you are only buying another 30 seconds over the 7.62 NATO...

Hmm. Considering the weight difference between 7.62x39 and 7.62x51, that just can't be right. I checked the numbers on that chart, and got significantly different results.

Their numbers:

182 - 7.62 NATO
385 - 5.56 NATO
210 - 7.62x39 (6.5 G w/123gr bullet)

My numbers:

178 - 7.62 NATO (M80 -- 392gr/rd)*
368 - 5.56 NATO (M855 - 190gr/rd)*
260 - 6.5 Grendel w/123gr bullet (268gr/rd)
274 - 6.5 Grendel w/110gr bullet (255gr/rd)

Going by their time figures (which also look to be off by about 25%), it gives:

7.62 NATO -------- 3.0 min
5.56 NATO -------- 6.1 min
7.62x39/6.5 G 123 - 4.3 min
6.5 G 110 --------- 4.6 min

Advantage is still to 5.56 NATO, but not quite as overwhelming.

* Weight data from TM43-0001-27