[BlazingArizona]

The one with the AK-47's was Guns of the South which has no sequels.

GOS is still the first book of the series. With the second book (I think it was "How Few Remain"), the outcome of a sovereign Confederacy in GOS is referred to, but the time-traveling Afrikaners had been quietly replaced by Lee's lost orders as having led to a victorious South. My impression is that Turtledove had gotten flak from Confederacy buffs who objected to the need for foreign help in a South-wins scenario.

[RebelBanker]

How Few Remain is not a sequel to Guns of the South. Turtledove used the same general idea ("What if the Confederacy won?") but the actual stories are unrelated.