I still say it is the bullet, they didn't work as handloads in my .300 Savage with 150 grain until I sorted them by weight to get 1-1.5" groups. I tried .270 150 grain factory ammunition in a TC Venture rifle shot right at 1.5" groups. I also tried 140 grain 7-08 ammuniton in a Stevens 200 and it grouped no better than 2".
In fact the only factory Remington ammunition that has ever grouped well for me is the 200 grain .35 Whelen load, both of my Whelens will do less than 1" for three shots with it. The only reason I bought the Whelen amunition is that one day I walked into Dicks and they had it on sale for $9.99 a box so I bought all 200 rounds and all the boxes were from the same ammunition lot.
I don't care if if 3% is standard deviation or not for bullet manufacturing. I'm not going to use Remington Core Lokt bullets for reloading or in factory ammunition for anything other than plinking. It just not worth it to me, and it isn't a big jump in price to step up to a Sierra, Speer, Nosler, or Hornady cup and core bullet and I've never had the problems finding a good group with theses bullets that the Remington bullet gave me.