While the antoninianus (double denarius) had been around since 214 AD the coins we are likely to find in these lots are the silver-coated bronze antoninianii of the late Empire.
Valentinian begat Valens, Gratian and Valentinian II. In the chart above I list which reverses are usually found on the coins of which Emperor.
It isn’t at all conclusive, but I hope it will help.
Locate the name and look for the all-important “N” which makes the difference between “CONSTANTINVS” and “CONSTANTIVS”.
Coins of Crispus and Constans are easier to pick out by counting the letters. After the death of Constantine his three remaining sons inherited the Empire.
Although coins from before the Constantine era sometimes appear in Uncleaned lots, they are so varied that producing a quick guide would be impossible.