Several of you have mentioned the 6.8
I do not have one so no bias here and I think they are a great cartridge. I have not met a cartridge I do not like, by the way. There have been many great cartridges that have died over the years (remember the 30 Remington?). Some times I buy a gun in a odd ball chambering. I have a couple of 221 Fireballs. They may go away some day too, but I can make cases out of 223 and they are not going away. The reason there are as many guns that are available in 6.8 is that the manufactures thought is was going to be adopted by the military as a replacement to the 5.56. The military has not fully endorsed it yet. If they do not adopt it as a standard volume cartridge, I think it will die. If they do it will take off and be as popular as the 308. It is simply a supply issue. If you can buy cheap military surplus cases or ammo it is assured that it will live a long life. It has a (non-standard) case head. I mean it is not a 308 or 223 size or of the basic belted mag. I thought about getting one, early. This was when the gun writers were all hyping it. It could shoot as flat as a laser, hold .25 MOA and kill deer like lightening out to 300 yards
I could buy a gun, but could not get ammo or cases or make cases to load with, end of that thought. It's bullet range is the smaller 270 stuff, because it was not designed to shoot the heavier bullets. It would make a good low recoiling deer rifle, but there are so many that fall into that category. The 243, 260, 6mm Remington 7mm-08, 250 Savage, 257 Roberts, 25-06, 30-30, 6.5 Swede just to name a few. Some of them are on their way out too. I do not think the 250 Savage, 257 Roberts or the 260 has much life left, for instance, even though they are all great deer rifles. The point is, it is very crowded in this category. The bullets are too big and too slow to make it as a varmint cartridge. That category is even more crowded. From the 22 rim fire through the 25-06, there a lot of cartridges. So unless there is a compelling reason I am not aware of, it is going to go the way of the dinosaurs. That is too bad, it is a great cartridge.