Unless you have a freak of nature the SPS isn't free floated. If you use a sling, changes in sling tension effect the barrel differently causing a drastic POA/POI change. If you're shooting with bags or bipods, changes in your forward/downward pressure (don't try to free recoil 308, doesn't work) can cause a similar change.
Don't over clean the barrel either, my rifle has been cleaned 3-4 times in 1500 or so shots, excluding the time it endo'ed into the mud at a competition. The .3" and .4" groups I posted were with 3-400 rounds down the tube. Shoot till accuracy drops off and then clean it.
For gods sake adjust the trigger if you haven't already. If you need help just let me know. If your glove is too fat to fit in the trigger guard, get thinner gloves of even better, a shooter's mit. My trigger is around 2lbs, about as low as you can get with the average stock trigger and light enough for me to keep sub 1/2MOA @ 300 yards.
Make sure the barrel's crown is mint and square. It really doesn't matter what angle it is at (target/recessed/ect) as long as the transition is crisp and even.
See if you can get a limb saver recoil pad to replace the original pad. I know the recoil isn't bad, but it sure doesn't hurt accuracy to spread the recoil over a longer time (the pad squishing).
Lastly, are you capable of shooting sub MOA with other rifles? 2-7 isn't alot of magnification, gotta have a firm grip on the basics.
The only stuff I haven't loaded that went through my rifle was Federal Powershok, 175 grain I believe. It shoot MOA or better as well out to 200 yards (as far as I shot it out too).