A lossless Random Access Channel (RACH) procedure is described for a wireless communication network. The method includes determining whether size of an uplink (UL) grant is less than size of a Medium Access Control (MAC) layer protocol data unit (PDU) of a Msg3. In response to determining that the size of the UL grant is less than the size of the MAC PDU of the Msg3 performing one of: rebuilding the MAC PDU of the Msg3 using one or more MAC Sub PDUs (SDUs) based on the UL grant and transmits a rebuilt MAC PDU of the Msg3; initiating new RACH procedure; and updating one or more MAC CE in the Msg3. In response to determining that the size of the UL grant is not less than the size of the MAC PDU of the Msg3, updating the one or more MAC CE in the MAC PDU of the Msg3 based on values of the UL grant and transmits the updated MAC PDU of the Msg3.