I bought my MEC ( Mayville Engineering Company , Mayville WI) 600 Jr in 1974 when I also bought a Rem 870 Wingmaster 12 gauge. Back then I reloaded field loads for pheasant, ducks , and geese. That was pre- steel era. I shot Trap some, so I got a charge bar for that. Back then the charge bars did NOT have powder bushings, I still have a couple of them-- but do not use them. The only time I had shot spilling on the floor was with # 5 copper plated shot. So I just spun the shot drop tube so that there was no bridging , and prevented the shot from dropping after the drop tube was above the shell casing. In about 1997 when I got a Rem 1100 LW 20 gauge, so I got 20 gauge dies. You don't want to change them back and forth with 12 gauge dies, as it gets to be a pain . For awhile in the mid 1970's I had a 10 gauge, and bought reloading dies, I finally sold the dies in 2014 because I sold the shotgun in the late 1970's. My son began shooting Trap, and BORROWED my Mec 600 Jr. I finally bought him a MEC progressive Grabber in about 1992 to get mine back. Four years ago my son gave me the Grabber because he didn't use it . Now the 600 Jr is set up for 20 gauge, and the Grabber is for 12 so there is no more die changing. I have more shot spills with the progressive Grabber than I ever had with the 600 Jr. So I mounted the Grabber to a 12 inch wide board , and built a 5 1/2 inch high wood box fixed to the 12 inch wide board. I made the 12 inch wide base longer than the surround so I could clamp the front and back on a table.
So why do I reload. In 1996 the radiological lab I worked in closed. I was there till the end cleaning up. They had a sample containment vessel that had double walls with about a 2 inch space between them. The outside of the vessel was about 2 feet square, and it was on heavy duty wheels. The used lead shot for shielding in the vessel. There were about 6 bags + 1 part bag of shotgun reloading shot left over after the vessel was filled . I asked about them, and I got them free. The asked me If I wanted the shot in the vessel because it was never used and was not HOT. But back then shot was about $11 to $12 a bag so I just took the bags. Fast forward to 2016 then I started shooting Sporting Clays and Trap, those bags didn't last too long. Now I buy shot at the club I shoot at. Last December I went to Palmetto State Armory and the must have been getting out of the reloading business, or the Green Dot they had was not selling, so I payed $15 a pound out the door, including tax. I got all 6 pounds they had because it usually costs about $25 including tax. So now I have a powder, shot, and wad load that patterns great out of my Beretta Silver Pigeon Sporting 12 gauge. It is equal to the high end factory loads.
So I reload to get the best pattern out of my shotgun. The 870 liked different loads than the Beretta. So there you go. Just go to Home Depot or Lowe's and get a 36 inch roll of rosin paper, or paper that is used to protect floors during construction. Put an orange rifle shooting dot in the center of a 36 by 36 inch piece of paper and mount it to a wooden patterning frame and try out your loads to see what patterns best. Checking out how your shotgun shoots is just as important as how your rifle or pistol shoots with selected hand loads. BUT as stated in previous posts, do NOT alter the loading recipes in the reloading books. You can also go online to Alliant or Hodgon powder sites and print out loading recipes for the brand of hull and ounce loading you want to use. They will give you choices of powder in grains, which primer, and which wad for several different load speeds.