I have two Dillon 550s and a square deal press .I have used them for 25 years they are far from perfect to say the least .Their famous for spilling powder and flinging the powder measure off .I actually stretched my 550 press trying to form brass on it so you need a regular press if you are going to format rifle brass. I WORE my first one out from that brass forming not made for that .They work pretty good with new brass if it's starline but alot of brass will give you total fits seating primers that's the other thing bad about them that primer system is not that good I has tons of problems with it too. HORNADY brass and dies gave me fits on my Dillon I stay away from them total junk .starline brass is awesome no problems from it It's hard to load little cases on the 550 too will wear your fingers out on anything littler than 357 .It's giving me total fits with 10 mm about to give up loading it .I had good luck loading 454 with starline brass 41 mag with starkine 357 rem max with rem brass .223 is terrible to load on it if you have once fired range brass I just quit loading it