The Redding 'S' full sizing bushing die is a great tool that gives you the ability to set consistent desired neck tension for your individual application. In the case of autoloaders, setting a neck tension of .003" can circumvent the need to crimp your cartridges. Crimping bullets without a cannulure can distort the shape of the bullet, and it will look like this:
This was a 168 gr SMK after applying a moderate crimp; the bullet has an hourglass shape to it.
Anyway, there is something you should know about the bushing die. Past a certain value of the bushing on the low end, the bushing will appear to not be doing its job. For example, I am loading SMK 77s in Lapua brass for my AR. Loaded .223 Lapua brass yields approximately .250" neck diameter, so I am using a .247 bushing to give me the desired .003" of neck tension. I mic a case just to see what the diameter before sizing is, and I get this:
It measured a bit over .252, so I size the case in the die, and mic it to check the neck diameter. I am expecting .247" but instead, I get this:
Why did I just get .24865 with a .247 bushing? What is happening is that the expander ball is blowing the case neck out after it was sized to .247. So to get the desired .247 neck diameter, I can do a couple of things. I can shave a bit off the carbide ball, but I really don't want to mess with that. I simply remove the carbide expander ball and run it through again. I don't skip the expander ball altogether, because I want to get any deformities out of the mouth so they are not transferred to the bullet when seating, causing inconsistent neck tension. This is what I get after the second sizing:
Pretty much dead on now. After seating the bullet, this is what I get:
.250 right on the nose. With .003" of neck tension, I don't need to worry about the bullets unseating during the violent action of the bolt. So be aware that if you are using a bushing die, and your neck diameter is bigger than the bushing, you need to remove the expander ball or shave it down to achieve your desired neck diameter.

This was a 168 gr SMK after applying a moderate crimp; the bullet has an hourglass shape to it.
Anyway, there is something you should know about the bushing die. Past a certain value of the bushing on the low end, the bushing will appear to not be doing its job. For example, I am loading SMK 77s in Lapua brass for my AR. Loaded .223 Lapua brass yields approximately .250" neck diameter, so I am using a .247 bushing to give me the desired .003" of neck tension. I mic a case just to see what the diameter before sizing is, and I get this:

It measured a bit over .252, so I size the case in the die, and mic it to check the neck diameter. I am expecting .247" but instead, I get this:

Why did I just get .24865 with a .247 bushing? What is happening is that the expander ball is blowing the case neck out after it was sized to .247. So to get the desired .247 neck diameter, I can do a couple of things. I can shave a bit off the carbide ball, but I really don't want to mess with that. I simply remove the carbide expander ball and run it through again. I don't skip the expander ball altogether, because I want to get any deformities out of the mouth so they are not transferred to the bullet when seating, causing inconsistent neck tension. This is what I get after the second sizing:

Pretty much dead on now. After seating the bullet, this is what I get:

.250 right on the nose. With .003" of neck tension, I don't need to worry about the bullets unseating during the violent action of the bolt. So be aware that if you are using a bushing die, and your neck diameter is bigger than the bushing, you need to remove the expander ball or shave it down to achieve your desired neck diameter.