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

[Tony Williams]

I see. When you wrote, "The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them," I didn't realize you were referring to only two existing weapons.

Yes, the Mk17 rifle and Mk48 machine gun should be easily adaptable to a new, longer cartridge. It seems like that will incur significant penalties in weight and bulk, though.

Any rifles and MGs designed for 7.62x51 should be adaptable to the new round. I suggested the FN pair simply because they are the two most obvious ones, being recently designed, in military service, and lightweight for the calibre.

I think if I were to opt for a longer cartridge, while still keeping minimum size and weight of both guns and ammo, I'd consider resurrecting the 1970's 6x45mm SAW round.

That was a good cartridge for its purpose, but I think that it is probably too small and lacking in power to be a credible replacement for the 7.62x51.

Don't forget that I see a new conventional round as being a half-way stage to something like LSAT. I believe that it is necessary to prove the intermediate round concept with hardware people can take out and use, before committing to introduce a whole new technology in the calibre. That means a conventional development path using existing weapons.

If LSAT fails for any reason, then other ways of lightening the load can be tried with the new conventional round - stainless steel cases or part-polymer ones like this one: http://www.pcpammo.com/index.html