Reliability　growth　test　is　a　common　method　to　evaluate　complex　electromechanical　systems　in　mechanical　engineering.　Reliability　growth　models　are　usually　used　to　predict　the　reliability　index　of　systems　after　the　reliability　test.　AMSAA　(army　materials　systems　analysis　activity)　projection-model-stein　(APMS)　model　is　widely　used　for　delayed　corrective　strategy,　since　it　only　requires　limited　assumptions　but　covers　all　failure　data.　However,　there　is　a　controversy　about　whether　the　Stein　factor　introduced　in　this　model　is　reasonable.　To　alleviate　the　problem,　an　APMS　development　model　is　presented　in　this　paper,　because　different　types　of　parts　have　different　inherent　failure　mechanisms.　The　study　showed　the　projection　results　of　the　proposed　model　are　credible.　Moreover　the　Stein　shrinkage　factors　were　more　reasonable　and　acceptable,　as　they　were　derived　from　the　components　with　similar　inherent　failure　mechanisms.　These　provide　a　technical　foundation　for　the　wide　application　of　the　proposed　model.　©　Published　under　licence　by　IOP　Publishing　Ltd.