The 6mmX223 can push a 70 grn 6mm bullet at about 2700fs, much less effeicient than the 77/80/90 grn SMK already in use in the 223/556, don’t even try seating a 107 SMK with the expectation velcoity past 2000fs!
Indeed. One of the contenders [submitted by Gene Stoner's ARES, I believe] during the SAW trials used a 5.56mm case with the neck opened enough to take a 6mm bullet. But I think the idea was to get a tracer bullet with a tracer burnout distance beyond 900 meters as much as for other external ballistic improvement. It's of course a lot easier to make a barrel change on a Minimi/M249 SAW than on a M16 rifle.
Again, no free lunches-trade capacity for bullet diameter.
An improvement on one side of the scale will certainly be met with a tradeoff of some sort elsewhere, unless there's a major materials/technology breakthrough. No argument from me about that.
You kinda lost me-use the 5.45x39 mmm with a .277 diameter bullet? You would be losing more case capacity than if you wnet with a 6.8x223 (45mm case), I think.
Correct. But it would be an improvement for the AK family platform, probably using existing AK74 magazines. At the very worst, magazines for the 5,56x45 AK variants might be used, or new ones developed.
There are a few dedicated 6mm cartridges being used in High Power Competition in the AR-the 2007 National Match Rifle Champ (Carl Bernosky) used a 6mm Hagar, not too sure of the case length, but the OAL must be AR mag length for use in the rapid fire stages....
Yep. And 6mm Tubb, the 7,62x39mm/M43-derived6mm PPC,and there's 6mmAR, intended specifically for the M16/M4 platform. And stepping things up a notch, the 6,5 Grendel.
Bottom line is the 233/5.56 mmx 45 is probably the most mature cartridge since the 308/7.62 (full course 200-600 yd match competition drives designs to the edge of performance, occassionally past it!)
Nothing to stop you from creating a 6.8 x39 mm, but it will be a lessor cartridge than the 6.8 or the 5.56 already are;
Yep. But it could well be an improvement over the 5.54x39.5 Soviet
Rough interpolation would indicate that it could not exceed ~2450-2500Fs (gas law rule of reduction of bore diameter compared to existing rounds always yeilds less velocity from a similar platform profile) with a 115 grn bullet, and AK/SKS platform accuracy is nothing to boast about either.
Concur, for the most part. Though accuracy concerns are more an issue with rifle accuracy than required beaten zone effects for a SAW, as per the US *Project Salvo* efforts of the 1960s-'70s.
The 5.56 with advanced bullet design (77 SMK) still is the best combination of performance, capacity, reliability and accuracy compared to the other combat options.
If you want a 30 cal (762x51, 762x63) performance step up to a proper platfrom, remember.... no free lunches for the dogs of war! (Democrat party planks notwithstanding....)
Molom Labe!
I'm not so certain it's all that cut-and dried. From the British thoughts circa 1910 regarding a possible pre-WWI .303 SMLE replacement that became the Pattern 13 Rifle of , to Pedersen's .276 cartridge used in the first Garand rifles, to the Post-WWII British circa-1945 Armament Design Establishment's Ideal Cartridge Panel development of the .280 cartridge [280 Mk1Z/(7 x 43 mm)]for the EM1 and EM-2 designs that would have become the British *Rifle No. 9* NATO rifle, there's been a lot of interest in something in there somewhere between a .22 and .30 caliber hole. Oh yeah, and the old Navy/Marine straight-pull Lee rifles and Colt Potato Digger LMGs of the Boxer War period. 