you need to know what speed your doing now. a duplex doesn't always mean more speed. more accurate or fires every time yes. I bought a crono so I could test loads with mine.im shooting 43g of n110 with a 250g SST.2320fps . 2600 and change with same powder and a 240g xtp. I would have thought the SST would have been faster based on the loading pressure but strange things happen .