To find how many pieces of candy there are per ounce in the jar, you can divide the total number of pieces of candy by the total weight in ounces.
Number of pieces of candy per ounce = Total pieces of candy / Total ounces
\[ \text{Pieces per ounce} = \frac{252 \text{ pieces}}{14 \text{ ounces}} = 18 \text{ pieces per ounce} \]
So, the answer is 18.