The precision measurements of U3O8 and Ra(eU3O8) concentrations were evaluated in 23 geological rock samples by high resolution gamma ray spectrometry (HPGe) using two P-type HPGe detectors. The use of Detector 2 (DET2) (GC5019) has increased the sensitivity by a factor of two for both the measurements in comparison to Detector 1 (DET1) (GCD30180). The Minimum Detection Limit (MDL) and Limit of quantification (LOQ) for U3O8 in DET2 has increased significantly because of negligible background counts in 1.001MeV ϒ energy peak (0.838% gamma yield). The MDL for Ra(eU3O8) measured by 0.609MeV and 1.760MeV has not improved significantly due to the high background counts in these energies whereas LOQ has improved appreciably. DET 2 has given higher level of confidence in reporting the analytical results with acceptable repeatability due to the decrease in uncertainty of the measurements.