, or if you are casting them yourself, you will need to size them.
Like Brent said. If you're casting your own they'll need to be checked either for normal acceptable size or against your throat diameter. All barrels are slightly different in size. One of the benefits of casting you own is being able to better fit your particular gun. I've got some guns that the as cast fits them perfectly. Others I resize. There's basically two schools of thought or practice for resizing. Both resize about the same by squezzing the bullet through a resizing die. The big difference is how they apply lube to the bullet. But these are considerations more appropriate for precision shooting not plinking and hobby shooting.