Does anyone have any info on converting 25rd mag, (it has a stopper pin to make it 10rd mag) to 15rd mag. I would like to also make it a shorter mag for ease of shotting from bench the 25 mag is to long. NJ has 15rd mag restriction.

Tacticool22 has some blocks to convert a 25-round to a 10-round. It shouldn't be a problem to change the length on them to do what you want. As for shortening the mag, for just five rounds, personally it isn't worth shortening 25-round mags - just shoot 10 round mags.