I'm just saying that if you're going to go for a 6.8mm/.270" cartridge why not just go for a .270 Winchester or one of the 7mm/.284" rounds like 7mm-08. Then you have the option of loading down to 6.8SPC speeds and the versatility of a full power hunting cartridge. Actually when you think about it .277" is closer to a true 7mm(.280") than .284". I actually like the 6.8SPC, but much prefer the 6.5x39 Grendell and if you look into the ballistics and energy carry you will see why.
Also the velocity of the milspec 6.8SPC Matchking rounds we tested was almost a full 200fps below the advertised velocity of 2650fps so I am dubious of the claim that they hold M262 5.56mm trajectory. The Grendell is proven to be more accurate than the 6.8SPC and many of the SF guys prefer it. The Grendell can hold 0.5MOA out to 400m whereas the 6.8SPC comes in at just under 1MOA out to 250m, also the Grendell offers you a greater selection of bullet weights - from 108 / 110 to 144gr if I remember - and better sectional density and a BC of over 0.5 (the M262 5.56mm and M118 7.62 rounds give .36 and .49 respectively so it has a better ballistic coefficient than even the specialist sniper rounds). The Grendell holds velocity better and is less prone to yaw and tumbling, though there is a trade off in that some of the most accurate rounds need to start of yawed and be allowed to settle in flight - one reason why the Mannlicher SSG had been known to be more precise at 300m and beyond than at 100m, but that only comes in with long for calibre rounds and the 6.5 in 123gr and above gives that in heaps.
Of course the 6.8SPC will do the job and if that's your preference all well and good. I just think you'd be limiting yourself to a narrow velocity and bullet weight band when other cartridges of the same(ish) calibre offer more options. And I would wait to see which of the new cartridges wins the main contracts.
The 6.8SPC cartridge itself is designed specifically to fit the 'black rifle' AR15 / M4 / HK416 platform. And the ballistics are 'supposed to' match the specialist heavy 77gr 5.56 rounds so that the current line of intensifier and CQB sights can be used. I find that claim hard to follow. I know that the 6.5G and the 6.8SPC are in active use right now and being field evaluated. And there is a real battle between the arms companies like Knight's Armament on this who, just to confuse things further, are working up their own proprietory cartridge in 6x35mm. Blackwater back the 6.5G and rate it highly and they have a lot of influence in DC. Also the Germans are looking at 6.5G for the next generation of semi-auto sniper systems (SASS).
But back to the point - is the 6.8SPC up to the job of killing deer? Of course it is. Is it accurate? Yes. But are there better options out there? Yes; the Grendell being one and there are at least another 3 cartridges under development for the same application.
You might want to look into the new .300 and .338 Ruger Compact Magnums (RCM). I haven't handled them yet, but they look very interesting. Something else to consider.
Here are a few comparison ballistic charts between 5.56, 6.8SPC and 6.5G. New cartridges are an interesting subject. Apologies about talking shop. If you need load data for 6.8SPC I can send you the latest tests.
Whatever you choose good luck.
Craig