So this has been identified as the priority area for the organization to focus on. The authors and management decided to address the problem using Six sigma DMAIC, since the cause and solution of the problem were still unknown. As part of the define phase, a team was formed with the Assistant Production Manager as the team leader and seven other team members. The team decided to consider "plunger taper" and "foot thickness" as critical factors for quality characteristics. In the measurement phase they analyzed the data collected using the Minitab software. The overall repeatability and reproducibility values ​​of the gauge were found to be 9.71% and 4.1% for foot thickness and plunger web, respectively. The results were presented in the paper. As the next step of the measurement phase, the p-value was determined, which was less than 0.05. The p-value is the measure of the probability of obtaining the spot data if no real difference existed. Therefore, a low p-value indicates that there is a small chance of obtaining this data if there is no real difference. For the analysis phase, team members did brainstorming, in order to find the root cause of the problem, they also made a cause and effect diagram for the change in plunger taper and change in foot thickness. During the analysis, the p-value for ANOVA and for regression grinding material and barrel roundness were found to be less than 0.05, which confirmed that these two have a significant impact on plunger taper. During the improvement phase the team decided that there is no risk associated with any of the solutions found. They then prepared an implementation plan for all solutions with details of responsibility and expected implementation date. In the control phase we ensured that the benefits and knowledge gained from Six Sigma projects were maintained in the long term