It depends on what you're looking for. Jpcs are made to carry the bare essentials to stay light.
If you're looking to load up with 10 mags, a hydro, and a bunch of other stuff, it defeats the purpose and design of the carrier.
If you're looking to run 3 or 4 mags and a hydro, it could work.
A break down of what your looking to carry can go a long way on what we can suggest.