  This paper describes a bounded generation result concerning the minimal
natural number $K$ such that for
$Q(C_2,2R):=\{A\varepsilon_{\phi}(2x)A^{-1}|x\in R,A\in{\rm Sp}_4(R),\phi\in
C_2\}$, one has $N_{C_2,2R}=\{X_1\cdots X_K|\forall 1\leq i\leq K:X_i\in
Q(C_2,2R)\}$ for rings of algebraic integers $R$ and the principal congruence
subgroup $N_{C_2,2R}$ in ${\rm Sp}_4(R).$ This gives an explicit version of an
abstract bounded generation result of a similar type as presented by Morris.
Furthermore, the result presented does not depend on several number-theoretic
quantities unlike Morris' result. Using this bounded generation result, we
further give explicit bounds for the strong boundedness of ${\rm Sp}_4(R)$ for
certain examples of rings $R,$ thereby giving explicit versions of results in
an earlier paper. We further give a classification of normally generating
subsets of ${\rm Sp}_4(R)$ for $R$ a ring of algebraic integers.
