The aim of the paper is to present the research procedure to improve performing mechanical tests. The article shows the results from experiments carried out with the use of reference objects and inter-laboratory comparisons. Details of the research technique for determining the mechanical parameters of strength screws and testing technical springs, are presented. The tensile characteristics of the screw material are provided with the indication of all the necessary mechanical parameters important for engineering practice, i.e. within the elastic and elastic-plastic range. In the case of the spring, the values of its deflection are presented, resulting from multiple loading to a specific force value and subsequent unloading. The obtained results are compared with the properties of the reference object using mathematical statistics and the requirements of the standard on proficiency testing. As a result, the competences of the research teams in the scope of performing the mentioned types of mechanical tests are confirmed.