Let $R$ be the Iwasawa algebra over a compact, $p$-adic, pro-$p$ group $G$, where $G$ arises as a Galois group of number fields from Galois representations. Suppose $M$ is a finitely generated $R$-module. In the late 1970’s , Harris studied the asymptotic growth of the ranks of certain coinvariants of $M$ arising from the action of open subgroups of $G$ and related them to the codimension of $M$. In this talk, we explain how Harris’ proofs can be simplified and improved upon, with possible applications to studying some natural subquotients of the Galois groups of number fields.