I have the same rifle, model 700 sendero in 300 win mag. This was my first time reloading so I struggled as well as learned a lot during the handloading process. After about 2 months of playing with different powder amounts and bullet seat depths I developed an easy to replicate load. The sendero's big barrel is very picky about powder amounts. A half grain of powder was the difference between 2 MOA groups and 0.6 MOA groups. My consistent 0.6 MOA load was barnes 180g tsx with 71.0gr of IMR 4831, fed. brass and cci magnum primers. I just used the standard COAL which is 3.34" I think? I used the normal COAL because I was testing the different powder amounts and wanted eliminate other variables and when I got great sub MOA groups I figured why change the COAL . I was shooting at just above sea level in about 40-45 degrees ferenheit and the bullet was goin at 3860 fps out of the muzzle.
I've killed lots of animals with this bullet and it is a great load. It depends if you like the barnes or not though, I've had some great kills when shooting high shoulder, and the bullet punches right through the bone. I did however shoot a big bull elk at 425 where I hit just at the very top of the lung slightly behind the shoulder (about 6-8") and the bullet passed right through. It dropped the animal relatively quickly but the bull stood up after an hour like he was not that injured, a quick shoulder shot as I was walking up to him did the job though. I feel that partition bullet would have done the job on the first shot but in the barnes' defense, I missed my target. In other words, this is a great load, a big bull elk doesn't die easily, and you don't have to be scared of punching through that should on a quarting towards shot. I shot a big bodied muley buck at 350yds quartering-towards and the bullet passed through the shoulder, devastated the vitals, and continued to pass through the oppsite side hind-quarter right through the upper leg bone.
Give this load a try, it's very nice when you don't have to mess around with COAL. I am currently in the process of loading some berger 185 gr with h1000 and I am struggling with the COAL and it is very frustrating when you know that there are two variables accounting for innacuracy, COAL and powder amounts.
Cheers and Happy Hunting from Bozeman, MT
-Mack (Montana State University - Environmental Studies Major. Age 22)