Fire form 7.62x39 ??

[Trashy]

I would drop that cfe223 charge down as low as I could. If there is a neck thickness issue you can get into trouble quick with cfe223. The saami chamber spec for the neck is .275 and the cartridge neck is .274, measure the necks of a couple and see where you are before pulling the trigger on one just to be sure.

Edit: max case length is 1.490 so get those cases trimmed to about 1.480.