Interesting article in todays Janes. US is looking at the idea of replacing the 5.56 and possibly the 7.62 rounds with the 6.5 Grendel.

 Opinions?

ANdy

I'll post up the full article tonight when I get home……

ANdy

I like the 6.5 Grendel for its longer range capabilities.
But if 300yds and less is the goal, then the 6.8 is good enough.

Remember...

The 6.8 was created with terminal performance in mind.

The 6.5 was created with long range accuracy in mind.

The 6.8 has been tested (and works very well) from a 12" barrel.  More rounds will fit in a mag.

The 6.8 is compatible with all current 5.56 weapons.

The 6.8 is superior for combat use.

Besides beaten to death, both rounds make big sacrifices to keep the 5.56 lowers and stuff the max case volume inside. IMHO do over for a more effective overall shape, not the door wedge of a 7.62x39 but some .303ish taper can save lots of headaches in the field. A jump to 120gr should not be half-baked.

Part of the article discussing various calibres……



Maximise lethality

Concerns within the US military about the 5.56 mm cartridge have spread beyond individual complaints. A group within SOCOM has promoted the development of a new cartridge that could replace the 5.56 mm: the 6.8 x 43 mm Remington Special Purpose Cartridge (SPC). This fires a larger and heavier (7.45 g) bullet, which has proved to be considerably more effective in tests even when fired from carbinelength barrels. It has been specifically designed to maximise lethality within normal rifle ranges of up to 300 m, although in fact the trajectory and terminal effects rival those of the 7.62 x 51 mm M80 ball out to 500 m.

A rival approach has been the fielding in limited numbers of the new 5.56 mm Mk 262 cartridge, with a heavier (5 g) bullet designed originally for longrange target shooting. This not only has a better longrange performance than the SS 109/M855, it also fragments out to longer ranges. However, at 600 m the remaining energy of the 6.8 mm bullet is over 40 per cent greater than that of the Mk 262. Despite this power, the recoil of the 6.8 mm is much less compared to the 7.62 x 51 mm and the cartridge is compact enough to fit into adapted 5.56 mm weapons.

It has reportedly been combat tested in Iraq in modified M16s with impressive results, although confirmation is hard to obtain.

New challenger

More recently, a challenger to the 6.8 mm has emerged in the form of the 6.5 mm Grendel from Alexander Arms.
This is an attempt to match the merits of the 6.8 mm while providing even better long range performance good enough to completely replace the 7.62x51 mm.

The 6.8 mm Remington SPC is limited to relatively short bullets to fit within the maximum cartridge length of 5.56 mm weapons, so the Grendel has a shorter (39 mm) and fatter case, leaving room for longer, lowdrag bullets, which retain their velocity out to tong ranges.

Bullets of up to 9.3 g have been tested; with this loading the remaining velocity and energy at 1,000 m match the longrange 7.62mm Ml 18LR NATO round and are distinctly superior to the standard M80 7.62 mm ball. However, the optimum choice for generalpurpose use appears to be a bullet of around 8 g, which matches the M80's trajectory. The 6.5 mm Grendel is at an earlier stage of development than the 6.8 mm Remington SPC, however, and has not been tested as extensively.

One of the penalties of switching to a more powerful round has already been mentioned: the recoil will be heavier. However, the recoil generated by the 6.8 mm or 6.5 mm is similar to that of the 7.62 x 39 mm AK47 round, which has been successfully used in automatic weapons for over half a century, so it is clearly manageable.

Another is that the cartridge cases are slightly fatter. The 6.8 mm case is based on the old .30 Remington hunting round of 10.6 mm rather than 9.5 mm diameter, which reduces magazine capacity; a magazine similar in size to the standard 30round 5.56 mm one will take about 28 rounds of 6.8 mm.

A third drawback is that the cartridge is heavier, so fewer rounds can be carried for a given weight, although the force of that argument is much reduced if it is necessary to fire more 5.56 mm rounds to achieve the same effect.

The 6.5 mm Grendel round is fatter still (it actually has the same 11.2 mm base diameter as the 7.62 x 39 mm), so only about 25 rounds will fit into a standardsized magazine.

The ammunition is also slightly heavier than the 6.8 mm if heavy, longrange bullets are used. However, in the longer term it has more potential to replace the 7.62 x 51 mm and its weapons as well as the 5.56 x 45 mm family.

With regard to developments in non NATO European countries, it is interesting to note that although the Russians, inspired by the early reputation of the 5.56 x 45 mm, introduced their 5.45 x 39 mm cartridge in the AK74 some three decades ago, this has also acquired a patchy reputation.

Some users prefer the old 7.62 x 39 mm, which is still being offered in new weapons. The latest Russian rifle, the 5.45 x 39 mm AN94, utilises a complex mechanism to provide an extremely fast two round burst, apparently to ensure that at normal ranges two bullets will strike the target rather than one. The Chinese recently adopted a 5.8 x 42 mm round in the QBZ95 issued to elite troops, which is claimed to have a longrange performance superior to both the 5.45 x 39 mm and the 5.56 x 45 mm, although the differences are marginal as the 5.8 mm cartridge, despite having more case capacity, is loaded to a lower pressure.

What would be the penalties if the US (and presumably NATO at some point) were to decide to adopt a more powerful cartridge like the 6.8 mm Remington SPC or 6.5 mm Grendel?

Normally, such a change would be extremely expensive due to the investment in existing weapons and ammunition.
However, the US Army, joined probably by the other services, is proposing to replace all of its 5.56 mm small arms and does not have large stockpiles of 5.56 mm ammunition indeed, they recently suffered a shortfall due to high expenditure in Iraq. There is therefore a window of opportunity to consider the replacement of the 5.56 x 45 mm cartridge before the new rifle competition is reopened, during which time it would seem sensible to carry out exhaustive tests of the 6.8 mm and 65 mm rounds against the 5.56 mm Mk 262 before reaching a conclusion about the future calibre.

One thing is certain: if the US eventually orders a new family of weapons, whichever cartridge is chosen will be in service for decades to come.

Anthony G Williams is co-editor ofJane's Ammunition Handbook and coauthor of
'Assault Rifle: the Development of the Modern Military Rifle and its Ammunition'

Facts:

6.8 SPC and 6.5 Grendel are both MOA or better out to 600m.  Can anyone argue that this isn't good enough?

Beyond this distance, the Grendel holds its accuracy better, but both can hit human targets out to 800m or more.  The problem is that neither cartridge is going to cause a great amount of tissue damage at that distance, with the limited velocity available.  Without a CNS shot, you can't count on taking the bad guy out of the fight.

To date, there has yet to be a Grendel load that meets IWBA or FBI wound criteria at any range, from any barrel length.  The 6.8 SPC was developed specifically to give optimal performance (for its size and host weapon) in that same criteria, and subsequent testing has shown this to be true.

ARs with barrels as short as 12" will shoot a 115gr OTM bullet that is JAG-legal and will still fragment out to 150m or so.  How does the Grendel do from a 12" AR barrel?

It shouldn't be a surprise that the round designed for this specific need (combat, especially from today's shorter-barreled rifles) does a better job in that role than the round designed primarly for long-range accuracy (which it does very well at).

-Troy

Quoted: Anyone have a link to info on why 6.5 would not work in saw's and other mg's ? Both rounds seem like an improvement over the current  5.56 -

The case diameter of the 6.5 is too large for the M249 (remember, it has a bunch of linkage and so forth to feed the ammo), and it's extreme shoulder angle would not work reliably with the extreme harshness that ammo encounters in a belt-fed.  For the same reason, the Grendel would not work in some other 5.56 designs.

-Troy