Welcome to the forum.
Retumbo and Ramshot Grand are excellent powders for the 6.5 Wby RPM, both giving me well under MOA accuracy with 140 gr bullets in my Weatherby Mark V Accumark Limited.
Depending on the bullet, 64.0-65.5 grs Grand is giving me .5-.6" groups.
JD338
There are many variables such as
Seating depth, neck tension, primers and different lots of powder.
I strive for low ES and SD numbers but sometimes I've gotten a good group with high ES and SD's.
JD338
I have only had 1 rifle not like PTs, a Remington 700 VLS 22-250 and that was due to the 1:14 twist.
Every rifle I've loaded with PTs has shot MOA or better. Several have shot .5 MOA -
243 Win, 257 Roberts, 6.5 Rem Mag, 280 AI, 30-06, 300 Win Mag & 338 RUM.
As for your 270 Win, what powders have...
The 7mm 150 ABLR is my go to bullet in my 280AI delivering sub .5 MOA accuracy and DRT results on WT deer from 50 to 500 yards.
In the 7-08 you are on the right track for powder selection. I'd start with Varget and Ramshot Hunter. Your 9t is just fine for the 150 ABLR.
JD338
I used a Nosler 6.5mm 140 gr SB from a 6.5 Wby RPM at a MV 3034 fps to take a late season doe at 150 yards. I observed perfect bullet performance on a deer that went about 30 yards.
JD338
I can add the VX-3 1.75-6x32mm to the list. That one was discontinued a dozen+ years ago. Never made sense to me. Great scope.
Also the TMOA reticle should be offered in more models, down to 2-3.
JD338