Hugh probably knows many more of the particulars of Camp Delaware than I would. Having said that I would be willing to bet that Camp Delaware is a continued learning process much like Camp Chase and other prison records. The NARA in DC do have the complete mirco-film records of Camp Delaware. There may be as many as 10 reels as the Delaware system was fairly large. If it were me I would entertain looking at those records. NARA does sell each reel for about $80.00 so they are expensive. Some public libraries may have the collection? If they do then I would look into a possible inter-library loan? Just some ideas. I would agree with you that your soldier if taken to a Northern Prison after September of 1862 knowing where the 42nd Va., was located that it would be either Point Lookout or Fort Delaware. If taken to a Southern prison ie., court-martial etc again the records should be at the NARA in DC. As you know there were five Argabrights in the 42nd Va. Regiment of Infantry. None of them seem to be the same soldier and they all belonged to Company B. NO doubt relatives as was often the case.
The soldier was NOT taken to Camp Chase according to the Camp Chase Records, but you already knew that. I do NOT know when I will be at NARA again, but when I do go if you have NOT found your answer I'll try and dedicate a oouple of hours on the Camp Delaware micro-film.