Re: New reloader
+1 to what Jim said. Any grooves or digging into your copper are going to affect the bullets flight, especially at longer distances. It can also happen if your necks are way to tight on your brass... But that's very uncommon. If you are chamfering your case mouths and still having issues, get a rotary drill, chuck up a 3/4" socket and fill the socket with 000 or 0000 steel wool. Spin your drill up to high speed and push the mouth of the case into it for about 5 to 10 seconds. Check to see if the mouth is smooth. Seat a bullet and see what results you get.
Welcome to reloading. It can be a joy and a pain, but if you keep at it, it's very satisfying to create rounds that are devastatingly accurate out of your rifle(s). There are a lot of experienced reloaders here that will be happy to help you... But also, don't forget to search for answers because it's likely that someone else has had and asked about the issue you are having.