PDWs...and other small arms.

[JASmith]

...overall cartridge length will increase significantly, or the bullet will extend a lot further into the case, further reducing performance.

The principal driver for cartridge length is to more readily back-fit into existing 9mm firearms. Remove that constraint and things change.

Could this mean we have an opportunity to do for the PDW what you're working to do with the rifle?

Base a new design on plastic cartridges to favor ease of carry but don't get too greedy with ballistic performance? This could mean a stretched version of the 6.5X25, one based on the .401 Win, the 7.62X39, or one based on the .45ACP/7.62?

A big part of the weight penalty of the .45 was that 230 grain bullet. Bottlenecking to say, 6.5, and using 50-100 grain all brass, steel&brass, etc. bullets in plastic cases could allow reasonable velocities with an interesting combination of barrier defeat and lethality while remaining compliant with the Hague/Geneva interpretations.