I just started with a steel erection company that had no previous in house surveyor. They gave me their Nikon NPL-352 and peanut prism to conduct anchor bolt surveys to verify correct location. 

While conducting my survey, toward the end of the day and at the furthest distance of my survey, about 200', I was running into errors of about 1 inch. I took the Nikon in for a much needed calibration and the shop said nothing was too far out, I think they said 8'' I can't remember what way though. I also purchased a proper back sight prism with tripod, tribach, and adapter. 

The next day when I was in the field I back sighted to my prism, surveyed for approximation 3 hours, temperature rose about 15*f, back sighted on my prism and it was off more then 5/8 of an inch, everything was level and nothing moved. So I re-shot my back sight and went on my way. 

My questions are:

Is there something potentially wrong with my Nikon?

What could I do to further check potential problems?

Or is this a normal thing for Nikon/all total stations?

How can I minimize this error?

Any help or suggestions would be much appreciated.

Thanks, 

Patrick