 While IPSC Open limits the magazine length to 170 mm (approximately 6.69 inches), USPSA Open changed the maximum magazine length from 170 mm to 171.25 mm (6.742 inches) somewhere between 2004 and 2009.Confusingly, some 171.25 mm magazine setups are marketed and referred to as 170 mm while they in reality measure 171.25 mm, making their configuration illegal for IPSC competitions.Since the magazine tubes themselves always are shorter than 170 mm, the overall magazine length will be dependent on the particular basepad used.