I also tried it with dry firing, as soon as I pull the trigger, then it's just as tight to open the bolt. I've never touched the rifle except to remove the bolt to clean the barrel, but if I don't pull the trigger it's smooth to cycle the bolt handle.
Earl.
Mr. aceman;
I believe that Mr. quarterboredave is onto the correct path in that the bolt is stiff only when you pull the trigger.
When you do so, the main spring must be recocked and if the cocking cam is dry or the camming surfaces beginning to gall it will most likely be very tough to open.
As you noted, when you don't pull the trigger, cycling the bolt is not an issue and that may be because the spring isn't needing to be re-tensioned by a dragging cocking cam?
It couldn't hurt to check the action screw length either, but giving a bit of grease on the back of the locking lugs and the cocking camming surfaces would be where I'd start.
Hopefully that was some use to you. Good luck with your rifle
Regards,
Dwayne