So even if the O.R.'s are 100% accurate how do we know that all the material relating to any given question is there? For a fact we know not all related materials are avaiable at any single reference location. There are books and manuscripts and even first hand materials official information not previously known now available through the internet. How much "new" materials have shown up on this very site.
This doesn't not even take into account the "Political" positions that had to be protected. This subject of "Arming the Slaves" is one such political position which would contridict the notion that the slaves were willing to "run to the freedom of the Union Army". It raises doubts about the mantra that the War was fought to free the slaves if you admit that blacks were willing to fight for the south. Oh they are willing to paint the loyal southern black as being the misguided "Uncle Tom", because it paints those few blacks as being stupid and unaware of what was going on around them. Even at that we know that there were servants teamsters and cooks in Lee's army during the the Maryland and Gettysburg campaign. Why didn't they run away when they were in northern territory? Lee's cavalry certainly had better things to do than chase down every runaway slave in Lee army.
When you have statements about the armed blacks in Lee's Army from such persons as Frederick Douglas a reasonable person has to ask the question of what was he talking about? Were there armed blacks in Lee's army during the 1862 Maryland campaign? Or was Douglas lying? If Douglas wasn't lying then what happen to those records?