260 guy, hate to admit I never bought 120 NBTs, but did 100s as I got a STEAL on almost 2k of them years back when I had my 6.5-308 built. The 129s shot so well in it, and my '96 Mausers I never saw a reason to shoot the 120s or 125s. 120 CLs did a few deer in DRT, as they were cheap enough to beg me to try them. Accuracy was not stellar, but killing results were!
I merely compared the 125 to the 140 PT, but based on the experience I had w/129s on deer, I'd venture to say at 260/6.5 Swede speeds, there may be less difference than more, on how a 129 compares in wt. retention, penetration, and frontal diameter vs. the 125 PT. I'd not hesitate to punch an elk, blackie, or even Moose w/one.
Right now 130 ABs are doing so well, it's my 'go to bullet' for now. Later I may try the 140 versions, and when my Bartlein bbl coming gets chambered up, I can envision taking a deer w/Bergers 130gr as I hear they spell lights out also.
I like to experiment no doubt, but I as you Jeff found long ago the 129 is a hard bullet to beat for any 6.5, whether 8 or 9 ROT, and for most general Big Game. NEVER have shot a bad group in anything w/129s. That is referring to the SP, as there is a diff in the SST, I hear some say it's 'softer' and can imagine it might be, so I would simply use the old proven SP.
