The 1979-P Jefferson Nickel is not scarce by any means either in circulated or even in Uncirculated grades of MS60 to MS65. However, it is a very difficult date and mint mark to find with Full Steps details on the reverse design. Out of the hundreds of millions of coins struck for this date and mint mark, less than 100 total examples have been found with Full Steps details on the reverse of the coin.
Most coins with Full Steps details are in MS64 and MS65 condition. In MS66 with Full Steps it becomes very scarce with only about a dozen known and none being finer.