Good posts. I have a 6.5 x284 also and many other large rifles. The 300 mag will spank, for sure. I can always get better groups with the 6.5 than any other larger rifles. But for killing big animals take the 300.
I've been trying different loads also with my TRG 42 using 300 smk. I note the clip spring is very strong and feed ramp steep. This combo damages the tips of the bullet making accuracy at long range difficult. I had to work my clip to fix the problem.
As mentioned by other posters lighter bullets (less than 180 gr) do better in the 300 WSM. But for long distance shooting the 208 Amax runs a BC of .64 so it will do much better for long range any carry better in crosswinds and retain incredible hitting power. Haven't tried the 215 berger since...
Your 100 % right on the Norma and Lapua brass I've used both. Primer cratering evident. Your claims of 1000 rounds without throat erosion would have to be proven. Having said that I can see that you do know what your talking about . And of course we don't buy a Ferrari and drive it at shopping...
gun)Don't want to rain on the AM picnic but I was going to buy one of them hot rod units long ago also but after looking at the barrel life and price of brass, I went for the 338 Lapua IM. If shooting through 3/4 inch plates at 800 yds is your goal, it will meet that easily. I saved enough money...