Is 100% IRA possible in stock control?

First and foremost, let me share the meaning of "IRA", it means Inventory Record Accuracy.

Yes i think so, it is possible, provided that all the people involve in maintaining the records are responsible enough in doing their job correctly.  It is just a matter of maintaining a reliable record of the actual "INS" and "OUTS" for every transactions dealing with stocks/inventory.  The "Do it Right, the First Time Policy" should always be in effect so as to achieve an effective IRA.