Probably not. Even dedicated lowers have feeding problems with glock mags.
I have a PSA that would have OOB discharges until I sorted out the buffer system and the BCG. I have another with a QC10 lower that has FTFs with ETS mags but works fine with factory or Korean SGM knockoffs. I wouldn't expect problems from a JP, but if you build one, there's no guarantee that the parts from one vendor will work with another.
The fact that a few dumbasses cobble together shit that doesn't work does mean that G-mag-fed PCC's always puke. Your logic blows.