Might have been an idea to try the rifle cold, after disassembling and cleaning out the bolt.
That way you would know if that was the problem.
Trying it warm, you have no way of knowing.
It can be informative to leave whatever winter lube you are using outside if it is in the cold, or in the freezer. See if it stiffens up when cold. There are good lubes that work at a wide range of temperatures.