OK, I have reloaded quite a few straight walled pistol and M1 carbine cartridges, but am now starting to work on .223 This is my first experience with bottleneck cartridges. I have a good quantity of used cases that I have decapped with a Lee universal decapping die and have them all cleaned up nicely with wet tumbling using SS pins. After lubing a batch, I ran a few through my Lee sizing & decapping die that is supposed to full length resize the case and expand the neck enough to permit a bullet to start. I ran about a dozen cases through the die and tested them with a Hornady 55 grain .224 dia. bullet for fit. I could only get about a third of them to accept a bullet to start. I disassembled the die and it appears to be in good order. I measured the expansion/decapper rod and it is .223. A couple of the cases internal necks measured .219 - .221 after resizing. I am guessing the expansion/decapper rod is not thick enough to properly expand the neck. All my dies and single stage press is Lee. I bought these dies used, but they appear to be in very good condition. What say you that are experienced with bottleneck cartridges?

Bottleneck case dies don't flare the mouth, so you shouldn't be able to "start" a bullet into the case unless it has expanded the mouth way too much. The chamfer on the case mouth is usually sufficient to get a bullet positioned for entry into the case.

Brass springs back about .001, and since your expander mandrel has a .223 dia it should leave you with a case neck I.D. of .222, which would give you .002 of neck tension which is a good number. You are seeing anywhere from .219-.221 for .003-.005, and .005 is too much. I don't know what lube you are using, but get some inside the neck, as a dry mandrel can get sticky and give inconsistent results. Polishing the mandrel works well too. Just don't remove too much material.

Thanks for the reply. I am thinking of ordering a flaring die.

Lyman makes an "M" Die for flaring casemouths that could work, but it's really not necessary unless you want to shoot some lead bullets at some point.

OK, I ordered a new decapping/sizing pin from Lee for my die. Tried it out this evening with 3 different .223 used case brands: Federal, Winchester, and Lake City. Before running the cases through the die, I relubed both the cases and the inside of the die with a mixture of lanolin and alcohol. I did this both with the original pin installed and again with the new pin installed in the sizing die. After each run through, a Hornady .224 bullet will not start at all in the case. What am I doing wrong or failing to do here? I do now have a universal case neck expanding die that I could use, but that just adds yet another step. I know others do not have this issue. Again, this is my first experience with loading bottleneck cartridges. I have loaded sizeable quantities of pistol ammo with no such problems. Frankly, I am baffled. Please advise. Thanks!

I'm thinking FC363 is right, you need a tool to put a small chamfer on the inside of the case neck.
Link here

The neck is sized as a straight cylinder and it has to be slightly smaller than the bullet so that neck tension will hold the bullets in place.
The de-burr tool shaves off the square shoulder inside the neck and lets the bullet start.
Check your brass for a sharp corner on the outside of the brass as well and notice the tools for removing it.