Requirements for Replacement of Currently Issued 5.56 M-855 and 7.62 M-80.

[Tony Williams]

Ref Post #69 --

Thanks! I'll try to work that into the next weight requirement discussion.

Just to follow up on this: in average round figures and using brass-cased ammo, 5.56mm M855 weighs 12 grams, of which 4 grams is the bullet. 7.62mm M80 weighs 24 grams, of which 9.5 grams is the bullet. An intermediate round like the Grendel weighs around 18 grams, of which 8 grams is the bullet.

The plastic-cased LSAT 5.56mm round with a 4 gram bullet weighs 8.3g (in the MG application there is a further weight saving as the plastic links weigh only 0.5 gm each instead of 2.0 gm, so the total weight of 5.56mm ammo plus one belt link is 14 gm in brass cases, 8.8 gm in LSAT). So the weight of the case and propellant drops from 8 gm in brass cased to 4.3 gm in LSAT, a reduction to only 54%.

Applying this to the 7.62mm M80 gives you a reduction in the weight of the case and propellant from 14.5 g to 7.8 gm, for a total LSAT cartridge weight of 17.3 gm.

Applying this to the Grendel provides a reduction in case+propellant from 10 gm to 5.4 gm, for a total weight of 13.4 gm.

So on the basis of the assumption that the percentage weight saving for the case+propellant elements would be the same in each instance (which may be incorrect - there may be other factors I am unaware of) the weight of LSAT equivalents of the three rounds would be: 5.56mm = 8.3 gm, 6.5mm 13.4 gm and 7.62mm 17.3 gm. Or ratios of 1:1, 1.6:1 and 2.1:1.

To put it another way, for the same weight as 100 rounds of 7.62mm LSAT you would get approximately 130 rounds of 6.5+mm and 210 rounds of 5.56mm. These are not very different from the ratios between the current brass-cased versions of the ammo.