Here's a photo of 4 bullets from a screwdriver-blade-scratched Lee C309-170-F single cavity mold. The 2 on the left show the scratch in the mold. The 2 on the right show the scratch covered with a back mark so I can easily index the bullets into an indexed case.

Looking for some ideas on how to differentiate between the 2 bullets out of a two cavity mold.

I have read some ideas in th past that centered around putting a dimple in one cavity, but am suffering from CRS, and don't remember how it is done.

Any help here ?

On Lee aluminum molds I use a screwdriver blade and mark mid-way down the nose of one side of a block and centered in the block, ie., 1/2 way between the seams of the bullet. I etch just enough of a scratch so I can easily see it in a bullet.

In such a way (as method in previous post will do) that the loaded bullet may be identified. Consider a center punch - lightly - with one indentation per cavity number. Consider also warrenty.

I have not tried it, but would an engraving tool put enough of a line on the mould to be seen when cast?

Maybe I shouldn't worry about it.

I have a 2 cavity 358429 (nominal 170 grains) and the two cavities are exactly 2 grains apart.

Is that enough to be concerned about for 25 yard revolver work ?

I mark all my rifle mould cavities. A tiny tiny punch mark on the nose works. I've found that indexing definitely helps when I'm trying for top accuracy from a rifle.