Rifle cartridge

If we're talking current type of ammo, then there is no point in a change from NATO standards.

If.....if however we're talking about the either CT (cased telescoped) or CL (caseless), then the argument for a change of bullet diameter is strong and here is why.
Both these types of ammo (currently being developed for LSAT) are straight sided. When circular as cylinders (CT)or square as blocks (CL) these fore a change in the shape of the actual chamber.

Of the two the strongest rumbles are for CT with the US doing what they have with this since NATO was founded.
That choose for NATO based on their own industries needs and their prevailing prejudices. In this case (ha) that is for 6.5CT but the case is dimensionally the same as the 7.62 effort. In order to give a lighter (not much) round able to hit targets upto 1.2km away.
However. ....
There is good news buried in this because of the cylindrical nature of the case and chamber, permits a short case in the same chamber.
So a shorter cylinder would give a shorter range but less recoil and weight.
Conceptually a gun could be built to take both long and short CT ammo and 6.5mm types are ideal.

Well then....



Let us agree that a EU military could move to a intermediate solution in preparation for the later arrival of either CL or CT type ammunition for example.



Then ideally we'd choose a all up round that fits existing actions, this means total length and cartridge length should be within the action length of current rifle system designs.



Then yes, 6.5 Grendel is a pre-existing solution that fits a AK47 type action, which hasn't changed for the 5.45 by 39 as used for the AK 74 and successor weapons. There is a wide range of weapons now available with actions of this length.

A 6.5 by 44.7 type would fit current NATO 5.56 by 44.7 compatible actions.

And a 6.5 by 51 type would fit NATO 7.62 by 51 actions.



So since we're talking NATO countries being predominant in the EU, a 6.5 by 44.7 round can be produced with a overall length of 57.4mm, which will fit existing 5.56 actions of which there is a veritable plethora of options.

Ideally the LSAT CT 6.5 bullet in a 'normal' intermediate (assault rifle) case.

Within this there maybe some wiggle room, as for a longer bullet keeping this within the total action length may mean a case of anything down to 40mm, depending on the specifics of things. Furthermore the long bullet can be set deeper into the case if need be.



So I'd say the 6.5 by 44.7 EU cartridge resolves the weapon conversion issue, but making the changeover more about changing barrels than chambers or magazines or the stroke length the bolt has to travel which means either remachining components or buying new. A lot of modern rifles have changeable barrels as part of greater modularity anyway.

This could make for a fairly smooth transition, as potentially current magazines could simply be used for the new cartridge.

Those forces that don't have rifles with changeable barrels, will have to buy new. But even then this might be confined to the barrel/chamber, avoiding a complete change of rifle until later on.

Again a worse case would be a complete change of the 'upper' of a rifle, but again this constrains the costs as industry is already well set to manufacture new for an existing action length and all that is changes is the chamber and barrel diameters.

In Edit.
So my answer may already have been conceived of by SSK as the 6.5 MPC (Multi Purpose Cartridge), designed to fit the 5.56 by 44.7mm action of .223 NATO standard rifles, with a change of barrel and chamber. Though this seems to be aimed at 12" barrels for QC work out to 300myards.
However there is also the Sharps .25 SPC which is a .223 NATO case necked up to hold 6.5mm bullets.
There is also the Winchester Super Short Magnum.
Or there is the .277 Wolverine. This last one is VERY interesting, as it approached the performance of the 6.8 SPC. But it hasn't yet been submitted to SAAMI.
However a .277 with a 110 grain bullet would deliver much higher energy at 300m compared to 5.56 by 45 (44.7), 7.62 by 39, and  300 BLK.

So you mean to change barrel, chamber and bolt on every 5.56 NATO compatible rifle in service within the EU?

The chamber needs reboring to the new case dimensions as well as the barrel. The bolt needs changing as the rear diameter is greater than the 5.56 rear which is 9.58mm rather than Grendel's 11.15mm. Plus I seem to get the impression that a 'beowulf' bolt is made stronger as well.

Then why not just choose the 6.5 by 47 lapua?

See if you're going for new rifles rather than modified existing stock then why confine yourself to 5.56 by 45 action length?
Might as well go the whole hog and change the action length as well and then you have much more freedom to choose.
Lapua fits inside the 7.62 action too.

Cool, The plus side is also the rear face of the case is 12mm which spreads the loading over more of the bolt's face.

This also means its current 7.62 designs are options for the rifle.

If I was being more cautious, I'd say it's easier to convert from longer action legnths (overall cartridge length) down to shorter than it is the other way and thus might want a longer cartridge than the 7.62. The old Swedish 6.5mm by 55, is about 80mm long overall and has a 12.2mm rear diameter to the case.


One question...why 30mm by 113? That's ADEN/DEFA territory, is it worth the effort to move away from the 12.7 and 20mm?