Cord about .125 inch in diameter and .100 inch long seems to work best.

Old CH dies have a .124" plastic ball that works fantastic. I went looking around for bb's that size and they want $25 for 100 of them pretty much anywhere online. I had to look around for other ideas because lead shot isn't something I'd recommend as it smashes down in the side threads just as much as the bottom and eventually clogs things up so you can't even tighten the grub screw down anymore. This is a great fix for dies which I've lost the plastic bb's to (which happens more often than I'd like to admit) Thanks for the tip!!!

The reason RCBS is using brass set screws is to prevent damage on the die thread, putting something in between the thread on the die and the tip of the set screw is an excellent idea. The hex screw head got stripped on my .223 SB die from wear and tear and thankfully RCBS replaced the lock nut and they sent me a number of set screws.

Change the brass set screw with steel Allen set screw the brass will mash out in a few tightening.

What is the correct size allen key? Thank you!