New US Army Rifle

[mrclark303]

So guys,after 56 odd years, there is finally a replacement for the venerable M16 and it's variants in US Army service. A slow creeping replacement that is, with a brand new rifle and new calibre.

Sig's MX5 and their 6.8x51mm round will slowly roll out and replace the M4.

The MX5 appears to be a relatively 'safe' route to take, nothing overly revolutionary or risky, it's a aluminium upper and lower rifle, rotating bolt, short stroke piston design with controls that will be immediately comfortable to anyone used to an AR15.

The rifle uses both a non reciprocating side charging handle and a 'T' rear charger.

The biggest surprise is the calibre, so much for intermediate! 6.8x51 is a very powerful round by all accounts, very high pressures too...

You can bet all the major manufacturers are scrambling to design new rifles for the new calibre, possibly adaptations of AR10 designs, somewhat beefed up to take the chamber pressure of the new round.

I assume NATO will adopt the new calibre too, certainly the MX5 looks to be one hell of a piece of hard hitting kit, I would suppose the M240 'could' be re-barreled for the new calibre, if it can take the stress of the new round?

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[browningautorifle]

I assume NATO will adopt the new calibre too

I'll bet we don't. Not for 20-30 years.

[mrclark303]

It's interesting Jim, funny old world, we go from fully fledged battle rifles, to the intermediate cartridge and turn full circle back to battle rifles!

I guess America drums the beat in NATO and we all slowly fall behind and get into step... It's fair enough, they spend enough money to guarantee and effectively underwrite the rest of NATO's security after all.

I would hope the UK just buys the rifle off the shelf from Uncle Sam and converts to the new calibre as it becomes widely available.

It appears Sig have won the whole shooting match in the US, from new service pistol, to new rifle and LMG and designed the new 6.8 round too!

[Woodsy]

So the wheel has come full circle in the past 70 years! The British-designed .280/30 cartridge was rejected in favour of the 7.62x51, which in turn was replaced by the 5.56x45 (which went through a number of modifications) and we now have a composite (read expensive) cased 6.8x51 that is about 15% better than the original .280/30 but at a 40% increase in operating pressure. Why not just use a steel-cased 7/08 at about 65,000 PSI (or a similar sized 6.8 that will not fit lower pressure sporting rifles), essentially the same result at a greatly reduced expense. How much public money has been squandered on this bumbling mismanagement over the last century?

[RCS]

I always like the 7x49 developed for Venezuela and sold to them in the early FAL rifle which I believe was 30K in that order. Later on even Castro had one !

The Belgium FN factory took the American 7,62x49 case and necked it down to use the 7mm S12 bullet and you have the 7x49.15mm Liviano cartridge

photos: 7x49, 7,92x40 and 280/30 single photo is 7x49mm

[rcathey]

They say a military goes into war well prepared for the war that came before it.

A more powerful, longer range cartridge would do well in the Middle East.

Hopefully there won’t be a next large scale war to figure out if this was the right choice.

[mrclark303]

I think the idea of the very high pressure 6.8 x 51mm round is to allow it to perform well in a 13" barrel of the MX5.

It makes you wonder if it's a limitation of the round, imagine the pressure generated if it was fired through a 21" inch barrel!

It's hard to see it having a civilian application too...

A few further observations on the MX5, it apparently has two gas settings, normal and " make it work" even its jammed with mud...

It somewhat surprisingly got a forward assist and one interesting feature are replacement sacriffical structural points, designed to do the 'stretching' instead of the upper receiver..... Interesting idea...

[Daan Kemp]

Seems the Brits had it right when they went the 7mm way before WWI and after WWII. The new cartridge looks like it could be the 7mm-08.

[Gil Boyd]

Strange that those who should know better, who are highly qualified in their respective technical armaments rolls, always make hard work on selecting the right calibre. I am sure there are those on this site that will remember days gone by when weapons were built (as they should be) around the round to be used NOT the other way round.
Interesting times. The 7.62 x 51 was designed to stop a man in his tracks, these days they seem to be satisfied with the softer, feather approach......................... "Lets not hurt them".

I think I had better start drinking whatever they are having

[mrclark303]

I certainly wouldn't want to get hit by Sig's new 6.8 round Gil, it packs one hell of a wallop, designed to defeat modern body armour, so that tells you it doesn't play nicely with others mate!!