Hey Hairbarebunch,
I agree. Some more points of info however.
The 5 cm Kw.K. 38 actually was used as a standalone, albeit improvised, "PaK" as was the 5 cm Kw.K. 39 !
Basically these were both types of the aforementioned tankguns fitted with armour shields and a "bunkerlafette".
These guns were mainly placed in coastal defence works (usually concrete emplacements) However, I don't know wether or not the firing mechanism was changed, so these improvised "PaK's" may very well have used the electrically primed rounds.
The PzGr 40 (hartkern) rounds utilised another type of casing, equipped with a longer neck crimped to grip the projectile at the base and beneath the "bourrelet".
There exist both a short and long version of these cases, the short version only in use with the Kw.K 38 (electrically primed) and, its "PaK" dertivative" (however it is improbable that Hartkern rounds would have been used with the latter).
The longer version was in use with both the Kw.K. 39 and PaK 38, the main difference indeed being the electircal priming for Kw.K (and, again, probably it's "PaK" derivative ) vs mechanical priming for the PaK proper. I'm not sure wether or not these longer "hartkern cases" come stamped both "Kw.K" and "PaK".
And last, There was also a PzGr 40/1, a "Hartkern" shot redesigned to fit the standard Kw.K and PaK cases. (B.t.w. iff anyone has a 40/1 for sale, or any of the aforementioned Hartkern cases, I'd be very interested in buying them!!! )
greetz,
Menno.