There has certainly been a lot of confusion about whether Buford's men had single shot carbines or Spencer repeating rifles (as I learned in researching my ancestors' 8th IL Cav). It's too bad Foote never cleared it up in later printings or speeches.
Nevertheless, his writing and speaking style was superb, and the fact that he spent 20 years researching and writing his three volume narrative is impressive.
Some of the confusion might come from the fact that members of Custer's Michigan Brigade on the eastern side of the battlefield carried Spencer repeating rifles, or so I've heard.
Hats off to your brave ancestors in the 8th Illinois Cavalry. I understand that a few of my ancestors were in Ewell's corps opposing them.