Just remember the machine the manufacturer uses to load the slugs is more consistant with loading the exact way each time and it is with a shell case that has not been used.I have reloaded thousands of shells for my gunning club for our trap shoots (they were 7 1/2's) and some of the problems I would have are the shells would not crimp perfectley every time,the shell casing would stretch if it was a cheep brand,and the cost of buying powder ,primer,wad,and lead in bulk was expensive and it takes alot of time (what is your time worth).you also wan't your slugs to be accurate andmadeto perfection.Check out what suppliers you have around your area and see if the materials are available and at what cost. Check out nachez on the internet they have great deals on slugs.Good Luck