The "Bar-Dot" varieties of 1836 Half Dollars exhibit a small bar extending horizontally from the right side of the loop of the 6, ending in a dot. This anomaly appears on four different obverse dies, represented on five different die varieties (O-101, O102, O-118, O-120, and O-121). Different researchers have debated the meaning of the bar-dot. Some believe it might be a trace of a 4 from an 1834-dated die overdated in 1836. However, others argue that the odds of four different 1834 obverse dies being overdated in 1836 are extremely low. Another theory is that the bar-dot is a mark placed deliberately on the die by the engraver. Or, it could be a natural die flaw. Clearly, researchers have not yet reached a consensus on the cause of the bar-dot. No matter which way it turns out, the Bar-Dot varieties are very popular with collectors.
The 1836 O-118 Bar-Dot variety is fairly scarce but can be found in nice condition thanks to a small handful of Uncirculated examples. The finest certified example tops out at MS65.