Factory loads are what I would try next. If the same problem persists, then I would send it back to the factory.
It is not uncommon to find dies that will not re-size the cases down enough fit into the chamber, if they were fired in another rifle with a larger chamber.
The fact that you said you were going to try factory loads next, but you sized and reloaded some brass indicates to me that the original brass was not fired in your rifle, but you did say new WW brass.
If you have a micrometer, seat a bullet and measure the neck diameter. Subtracting .308 from your reading and dividing by 2 will give you the neck wall thickness. This should be about .015"
It could be that you have some cases that are too thick in the neck and cannot expand inside the chamber when they are fired.
"The bolt lifts easily, but it is difficult to extract the case."
Usually, if the cause is from too high pressures, the bolt will be difficult to lift. The fact that you feel the stickeness when you go to extract the cartridge, instead of when you lift the bolt leads me to believe that there is something besides the cartridge that could be giving you problems.
You said it is brand new. Did you clean the barrel and chamber throuoghly, making sure you removed all oil or grease?
