RonJ,
I believe that some K38's were single action only and could not be cocked by the pull of the trigger. But in those guns the hammer is completely back when cocked. I believe that the Factory sold the single action kits for user installation also.
It is also possible that the single action was an aftermarket modification. I have a .38/44 Outdoorsman with King accessories which has been so modified.
gennis,
If the hammer falls from the half cock position, I would be surprised if it would reliably ignite a primer. I would have the gun checked by a competent gunsmith before using.
Bob