I will be shooting at squirrels and PDogs. I guess I should have clarified that in the post. That information might have made the topic a little better. Maybe more will get involved in the discussion.
Also, if you build a heavy 6mm with a muzzle brake
, you can see where shots miss or hit much better than any .22 cal. My new 6mm project will weigh 32 pounds, and it will have a brake too.
The subject of burning barrels is usually a topic when discussing varmint shooting. However, at long ranges there are not as many shots taken. Also, must varmint hunters bring at least two and sometime three rifles during there hunts to allow their other rigs to cool. That's why I chose the 6x284 as the best overall long range varmint cartridge.
Now, if you only have one rifle to shot all day for varminting and there will be shots from 100 to 1000 yards, then I would say the 243 or 6BR would be the best.
Also, the velocity of the 6x284 is 200fps faster than the 6mm Ackley Improved and 400fps faster than the 6mm Remington. That's a big advantage at long range. The 6mm Ackley is an awesome cartridge too. I would have made it my # 2 pick, however, you have to do so much prep to the brass in order to shoot it.
I know there are other excellent 6mm cartridges out there, but when it comes to velocity, accuracy and retained energy, the 6x284 is the best IMO.
Regarding my current 6mm project, I am leaning towards the 6x284. However, I am still trying to gather info on the 6BR. I just really love the 6x284, because I ve seen it perform out to 1000 yards with excellent results. When using the 6x284, and pushing the 87grn V-Max at 3730fps, it's amazing to watch what it does to ground squirrels past 600 yards. Even at that range it destroys the little vermin.