I shot a buck last year with 16" 6.8 SPC and 120 gr SST with decent recent result and clear through penetration. The shot was through the ribs though as I was purposefully trying to limit meat loss. The SSTs have worked well for me in 6.5 CM and .308 on deer as well. I reload and the Hornady bullets are generally a little cheaper and easier to find and the 120 sst is available as factory ammo. They also shot well from both my 6.8 SPC and 6.8 SPC II uppers. Like most ammo/ reloading things they are probably in short supply currently.