The goal is to replace both 5.56x45NATO
AND 7.62x51NATO, but this imply a modified 7.62x51 battle riffle => heavier than carbines
7.62R obviously outranges any intermediary round
Nope. And same issue as 7.62x51 : too much recoil when fired in bursts. The reduced caliber reduces recoil and improves accuracy at long range. In fact, in 1000yards and 1km competitions, it's even smaller calibers that rule, like 6mm Benchmark and up to .250 with 640mm barrels
It happened when many said it wouldn't. The US military adopted not only a new service rifle but a whole new cartridge, the 6.8x51 also known as the .277 Fury. The gun is solid, but the 6.8x51 seems like a huge step backwards and the US military has abandon the assault rifle in favor of a Cold War era type battle rifle.
Good discussion to listen to all those who suggest Pakistan should follow the same path with this cartridges.
I thin they should have went for the .243WSSM : the 6-6.35mm are absolute winners in 1km shooting competitions, moreover, Winchester designed the .243WSSM to fit into a modified AR-15, mainly to allow women to hunt big game without the inconvenience of weight+recoil with either .308w (7.62x51 NATO) or .300 Winchester Magnum. Some laugh at the brass' shape but actually, it helps reducing recoil which is similar to the 7.62x39M1943 despite 50% more kinetic energy (!) 3000J is less muzzle energy than 7.62x51NATO or 7.62x54R but the far superior ballstics of the 6-6.35mm induce a better energy retainment during the flight, you can expect a 80 grains bullet still being supersonic at more than 1km, and it's more accurate with less drop than a .300winch-mag at 1100m... In other terms, you just need a single shot for a 300kg deer at 400-500m and you can hunt coyotes at 1000m while the .223R = 5.56x45 is a 300m coyote round...
So, nonetheless you have a mild recoil in selected-fire mode but you have also a true blue sniper round that fits in the M16/M4 as well as all NATO 5.56 STANAG magazines. The only issue is that you will only fit the 2 thirds of the rounds (sorry, I can't tell how much exactly, I don't own a 5.56 carbine to do tests) so it would be about 20-22 in an usual 30rds magz,, but there are extended magz around for long, even up to 150rds in double snails... So, just go for a 45rds 5.56 mag and get your 30x .243WSSM while a 100rds casket-mag should have smth like 65-70 rounds in...
Now it's a pity GIAT decided to close the MAS factory since, well, thanks to reinforced arms controls and no full replacement of the FAMAS F1 by the G2, the sales were in the abyss: the FAMAS G2 (only in use in French Marines) has a "sniper" version with... 620mm barrel which is only 88.9cm long...
At about only 89cm, it's OK for CQB, e.g. the HK G36K, which is highly appreciated by SWATs that want to pack more firepower added to AP capabiity the classic MP5 hasn't, is 86cm long but only with a 318mm barrel, moreover, even with the classic FAMAS barrel length (488mm), you still retain a riffle barrel but with a 75.7cm long riffle and the 320mm SBR version is 58.9cm long: both regular and SBR are shorter than a HK MP5... At the same, you have fast fire at 1000 rpm, and the 620mm barrel would be damn accurate at 1000m ...
The Tavor X95 seems also a very good candidate...
Even if this 6.8x51 will surely be an improvement, it's a pity that USA is MORE THAN 70 YEARS LATE on the Belgian and Brit ballistic researches that led to the FAL (which wasn't intended for the 7.62x51!) that competed for the NATO standard caliber in the early 50's while US imposed the inferior 7.62x51 through lobbying because it had similar performances to 30-06... When they faced AK-47s, they got that the full sized battle riffles like their M14 as well as the FAL or G3 sucked in urban/jungle warfare while the M2 carbine was outgunned... But again, they didn't listened to ballisticians since as soon as 1947, the .22APG would have allowed the M2 carbine to have similar performances to the AK-74...
Actually, there is even a wildcat of the .30carbine, the .25Garin with better kinetic energy than the 5.45x39M74 while, hey, .30carbine can fit in pistol grips, so, e.g. the HK MP7 or the STK CPW are able to be made as powerful as an AK-74U while being carried like big pistols in thigh holsters...
But hey, now everybody has 5.56x45, no, hell, no, USA will push to impose NATO with a caliber that needs a larger frame with 7.62x51 larger magazines while the 5.56 designs can easily modified for an even better round. OK, for sure, Colt, HK, FN, Steyr, Nexter, Dynamite-Nobel, Winchester,etc will be happy, but tax payers will be less happy and there was a mean to do it better and cheaper.
Actually, it's one of the issue with our US friends : they can afford throwing money by the window, we can't...