Sometimes the mag disconnect rubs on the front of the mag, and if that area on the mag body is rough, it can affect the "feel" of the pull.
Use your new magazines a bit, then check the front edge of the mag (about 1/4" to 1/2" down the body from the top) for a rub mark. Gently polish that area very smooth with small-grit wet-and-dry paper, then lube the bare spot (both for reduction of friction, and rust prevention). Try the mags again, see if that solves the problem (partially, or fully).
Mag disconnect can be removed on HPs, but it is easier to do on some models than others. If you can, have a pro shop do it (check with Cylinder & Slide; not sure if they'll do it or not nowadays?).