Regarding all of the questions I can remember after just reading the thread, here are my thoughts. And I'll start off by listing what experience I do have which is a good amount but half of what many have.
I've been shooting the 270 since the mid 80s. My first rifle was a 270. I've been loading for the 270 for 20 years and I've tried a LOT of bullets, and killed a LOT of game with just about any brand you can think of that is for hunting.
So, if a 243 or 243AI with a 105 Berger VLD can kill an elk at 1000 yards, so can a 270 with a 130, 140, or 150, whether we agree with the decision to use these calibers or not. That's personal choice. Me? I choose something bigger if I know I may have a long shot at an elk.
I have settled with, and highly recommend, the Berger VLD in 150 grains. I'm working on development with a new custom 270 and H4831SC and H1000 are getting in the high 2900s with powder charges still a grain or two less than the case will safely shoot. Still working on that, but if I'm guessing correctly and velocities keep rising at least 20fps per gr of powder, then we'll be right at 3000 fps or just over so long as accuracy is still there. I've already found a tack driver for my first 270 using IMR4350 and a Fed 215M primer.
Dies: I use Forster and Redding. Wilson dies are excellent too. I recommend you send your sizing die back to factory and have them hone the neck to where it squeezes your case .002 less than a loaded round. From there you have 2 choices. You can pitch the expander as you won't need it unless neck tension is too much, or you can keep the expander and runout will still be significantly reduced because it should open up the case mouth only .001. That has been my experience with multiple size dies in many calibers and in both brands.
OR, you can get Redding Bushing dies and use a bushing that will squeeze the neck .001 less than a loaded round. This works perfectly as well. The only time you run into a bit of a problem with doing these things is if you change brass drastically, like buying Lapua 30.06 cases and sizing them to use in your 270. I've done this for one rifle and you can either stick with the expander so it only has .001 neck tension or you can turn the necks, (or both). But Winchester brass works well, you just have to pitch the crap cases as you will get some.
If you decide to use a Berger VLD in 150 grain, I'd suggest you begin with H4831SC and H1000 and don't hesitate to try magnum primers either. For over 40 years, many 270 loaders have experienced better groups with a magnum primer, including myself. I'd also tell you that you can certainly use the IMR 4831 and 4350 as well, as I personally have not experienced major, even minor changes with POI and temp swings.
Barnes bullets: ...used a LOT of the TSX and some TTSX. Work like a charm and when they hit bone, it's like blowing through soup. Fantastic hard hitting bullet that drops deer and antelope like they got struck by lightening. Love them. Would not use either for shots over 350-400 yards. I got these bullets for close work, like shots under 300 yards and my preference is to square the shoulder with them, and NOT go rib shots behind the shoulder.
