Have to agree with Sparrow and presspass.
I will add a bit:
First, I don't have an R3A but I have used an R2A for several years and I think the metering system is the same for both.
With my camera, one thing I noticed is that(especially outdoor daylight and with wide angle lenses) the meter would act as you describe depending on how much or how little sky was in the frame. Which really means, I think, on just where I was pointing the camera. In other words, while the over all light looks much the same, it demonstrably is not equal. In practical terms this meant that my meter readings could change quite a bit if I angled the camera more or less towards the sky or the foreground. Or from a sunlit area to a shaded area.
Rather than chasing the meter, I have generally tried to meter my subject and not worry too much about the background or other areas in the frame that might not give the same meter reading.
When I was using the camera in auto exposure mode, I would meter my subject, then use the AE lock button.
Most of my cameras are meterless and since I have been able to get good results with out a meter, I don't get too upset when the meter in my Bessas jumps a little.
Hope this helps!
The path of excess leads to the tower of wisdom.
-- William Blake