I have to rugers. One 243 and one 308. Both have VERY long throats. The 243 factory bullets are around 2.610 oal. But i set them around 2.810 with 85 gr barnes x and their still jumping to the lands! If you dont handload sometimes the ruger is hard to make shoot factory rounds. My 308 ruger shot 175 blackhills ammo at 1 3/4 moa at 100. But MY custom loads of 175 i got 5/8 moa at 100 yards, thats a big difference!
yessir, without making hand loads, factory ammo is just a crap shoot that might never ever pan out, or maybe ya just get lucky. i don't trust luck, so i hand load. it is what it is.
for all my centerfire rifles, i always use a hornady oal comparator gauge. with my rar .243win, and sierra 60gr varminter boolits, they were touching the lands at 2.614" and i've had best accuracy setting that round col to exactly 2.598".