OK basically this is how it works. Each stage could be done separately on a single stage press or all at the same time using a progressive. The example given is based off of a Dillon 550B. This is the readers digest version and put in a format without all the reloading jargon. You can go to Dillon's website, download a 550 manual, and look at it while reading the different stages. This may help. I will work on putting pics in the email if I get some time tomorrow. LEE Factory crimp die set (4 die carbide set) used for example with the LEE powder die staying in the box since you must use the Dillon one on their machines. The press does come with one attached to the powder measure when the box arrives. These are the steps but it doesn't take place for all the reading that should be done to understand the right and wrongs as well as the safety safety safety. Its intimidating at first but after you load your first hundred rounds, you will wonder why you were ever stumped in the first place.
Stage I - This stage does 3 things when you pull the handle (Size the case, deprime, and prime). With an empty shell plate, pull the handle down which will raise the shell plate. Screw the sizing die so that it touches the shell plate. Now, put an empty cleaned case in the shell plate (piece of metal that holds the case in place - comes with the conversion kit from Dillon). Pull the handle down, the shell plate rises to insert the empty case into the stationary sizing die. The case goes fully into the die to take the case down to the size it was before it was fired (expands when fired) while the little punch will punch out the old primer. On the up stoke of the handle, the new primer gets seated into to primer pocket. Make sure you can feel the primer a little bit. If it goes in too easy, the case should be tossed. On a progressive press, you load 100 primers in the primer tube at a time The primers move into position on the down stroke and seat into the case on the put stoke. If you forget to seat a primer, you will wonder why you got all this powder all over the place. Its because its coming out of the hole that the primer should have been in. You also want to make sure the primer is seated flush. This is why some people use reloading boxes. The help to identify a high primer. I only use them to keep track of a new load I am trying out since I feel like I am working in a sweat shop in China putting all those rounds in their little holes.
Insert empty case into stage I
Pull handle to size and prime
Push handle forward to seat primer
Stage II - This stage does two things (bell the case and charge it). First it puts a bell on the top of the case. This is to have something for the bullet to sit on and so that is doesn't cut into the brass when it is seated on the next stage. The other thing that is done on this stage is dispense the powder. The powder dispenser is basically a hopper that drops a dialed in charge that you set. Screw the powder die (must be a Dillon powder die) in the second stage hole and put the powder funnel in the die. The powder funnel comes with the Dillon conversion kits and is what puts the bell on the case as well as "funnels" the powder in the case. Attach the powder measure on the die and finish assembly per instructions. Put a case from stage I in the shell plate and pull the handle all the way in the down position. The shell plate will rise and go into the die a little bit. Return the handle in the up position which will return the shell plate in the resting position. Keep screwing the die in a little bit until you get the bell you need or back it off if you have too much. Just need a little bit. You will get the feel of it. Too much and you will have a hard time getting the case into the next stage. Too little the bullet will fall off since it has nothing to sit on. Its not that hard to get the hang of it. There is a starter recommendation in the Dillon manual but you will find out what works best for you. On the up stroke, it pulls the case out of the die and resets the powder drop for the next round. Now add powder to the powder measure. Pull the handle, it will bell and drop the powder (I know you already belled but you have to bell again since it goes along with dropping the powder). Weigh the charge and adjust until you achieve the load you are using. Weigh and weigh again. If its not perfect, dump the powder out of the case and put it back in. weigh a couple more times just to make sure the charge is correct. Can you see the charge weight is important? Also its good to cross reference a charge weight between two references. A typo could mean a KB!!! Especially if the load is from a friend. Don't be scared to try peoples pet loads. They are some of the best I have ever tried. But please always check to make sure they are within loading specs per published manuals. When you get more experienced, you can play with pushing the envelope. When switching brands of powder in your measure, make sure you get all of it out. 5 grains of one powder could be a low charge but that same load in another powder could KB your gun. I have read where one guy switched powders and had a KB. They pulled the rest of the bullets and everything was OK. I suspected that he didnt clean out the measure good enough and it dropped some of the old power which would be at a dangerous pressure at the new weight. Just be careful. I played around with it to see if it could happen and it can.
Move case into stage II
Pull handle to raise case into die which will bell the case and dispense powder.
This is what the bell should look like
Stage III - This just seats the bullet to the depth you want it. With the shell plate empty, pull the handle to raise the shell plate. Screw in the bullet seating die until it touches the shell plate and back it off 3 full turns if using the LEE die set. Back off the screw on top of the die. Now put a case in the shell plate that has already been through stages I and II. Place a bullet on top of the case (I always look in the case to make sure their is powder in the case before I set the bullet on the case) and pull the handle. On the down stroke, the shell plate will rise. The case with the bullet will rise into the die. On the up stroke, the round (its a round of ammunition at this point) will pull out of the die. Take it off and measure the overall length with a caliper (need one of these things). It will be long because you backed off the screw a lot. Screw the top screw of the die in more to further seat the bullet to the depth you want (little at a time). Each time, put the round back in the shell plate and pull the handle down and up. Measuring each time. Stop when you have the depth you want.
Move case to stage III
Place bullet on top of the belled case
Pull handle to raise the bullet/case into the seating die.
Pic shows seated bullet
Stage IV - This is the crimp stage. The purpose of this stage is to take the bell out that you put on the case during stage II. Its not to retain the bullet although some people think it is. With an empty shell plate (no case) pull the handle to raise the shell plate. Screw in the die until it touches the shell plate and back off the bolt on top of the die. Put the round in the shell plate and pull the handle down and the shell plate rises (I figure you get this by now). The round will go into the die. While keeping the handle in the down position and the round in the die, screw in the bolt on top of the die until you can feel it touch the bullet. Pull up the handle to return the shell plate to its resting position. Screw the bolt on the die in additionally 1/4 to 1 turn. I usually do a little less than 1/2 turn. Put the round back in and pull the handle down then back up to complete the cycle. Take your calipers and measure the crimp (top of the case) on the round to see if you have it per your load data that you are trying to accomplish. To much crimp and you will dig the brass into the bullet. Too little and you will have feeding problems due to the bell. The nice thing about the Lee Factory Crimp Die is that you don't get over-sized rounds that can get stuck in your barrel.
Move case into stage IV
Pull handle to raise the round into the crimp die.
Thats it, you have a round made on a 550. Of course on the 550 you do all the stages with one pull once everything is setup. I broke the stages down as if you were setting it up for the first time. As you can see, most of the work is setup. Thats why I always recommend a turret at the very least. Don't have to mess with the setup all the time. Lee makes a pretty good one but its still 4 pulls of a handle instead of 1 for the same end result. The startup price is very small with the LEE kit. If you shoot more than 200 rounds a month, I say get the progressive. I would take a LEE progressive any day over a top end single stage or turret. Just my opinion.