I think that is important that you understand why one should avoid pushing case shoulders back (bumping) excessively. When a rimless cartridge is fired, the force of the firing pin strike, and slightly after that of the primer going off push the case forward in the chamber until the chamber shoulder stops it. This creates a momentary gap between the bolt face and the case head. As the pressure rises from the burning of the powder, the sides of the case body grip the chamber holding the case in this forward position, and with normal pressure loads, at some point the pressure is enough that the case stretches, just in front of where the solid head begins, back to the bolt face, very slightly thinning the case in a narrow band in this area. The first time that a case is fired, this may amount to a stretch of say .006 or so, but as a one time event, the loss of thickness is not a problem, unless it is repeated over and over, because the case is sized incorrectly, bumping the shoulder back too far each time. If this happens, the case will be gradually thinned, first showing a bright line in the area that is becoming thinner, and developing an indentation on the inside. This is called incipient separation. Cases that have this condition should be discarded. If the incorrect process is continued beyond that point, cases will crack, and their head separate from the body of the case, leaking gas, and leaving the case in the chamber with its head on the bolt face when the bolt is opened. There is some potential for the shooter being injured in an extreme case, but I have not seen this. Getting back to the incipient separation, the internal groove that accompanies it can be detected by straightening out a paper clip, putting a short right angle bend near one end, and pulling the tip up the inside of the case from the bottom. If a groove has formed it will be felt just off of the bottom.
If on the other hand the FL or body die is set properly, and the shoulder not pushed back (bumped) excessively, the stretching of the brass will be minimal, and cases will not be thinned near their heads excessively, resulting in long case life, usually to the point that necks will start to split from repeated sizings and firings, but if the chamber is not too big in that area, and the sizing process properly controlled, this may not be an issue for a great number of rounds.
You seem to have gotten the impression that you need to get a bushing FL die. While it will eliminate the need to use two steps (neck and body dies) when you size, beyond that, there is no advantage. You can get the same result with what you have. What you do need is a tool to measure shoulder bump, and to learn how to use that tool properly. Once you have one in hand, I suggest that you return to this forum for some coaching as to how that is best done. There are a few things that may not be obvious to the first time user.
