If you are committed to the 669 and 9mm Parabellum a few issues are involved in ammo selection to comply with the NJ laws.
1. Ammo must feed reliably in your pistol. My experience with the S&W autos has been generally good in this regard. Those I have used were reliable with just about anything I chose to feed them, including handloads of .357" SWC's intended for .38 and .357. I suggest that you try a few factory loads for function in your pistol, with an emphasis on large frontal area and flat point. Test each thoroughly to assure yourself that what you choose is 100% reliable in your pistol
2. I would avoid +P, not so much out of concern for the pistol but more from concern over excessive penetration. No point in launching the bullets at higher velocities and increasing penetration; the only real benefit of the higher velocities has always been in getting JHP ammo to expand reliably, and that factor has been taken away from you.
3. The 669 has fixed sights that are not readily adjustable (usually requires a file). Your ammo needs to shoot consistently to point of aim at reasonable ranges (25 to 50 feet). S&W, like most manufacturers, regulates fixed sight guns using the more common ammunition types, probably 115 to 125 grain in 9mm. Much lighter bullets are likely to shoot low compared to point of aim, and much heavier bullets are likely to shoot above point of aim, due to differences in barrel time during the recoil impulse. Make sure whatever you choose is capable of shooting to point of aim.
Will the law permit you to keep using your standard capacity magazines, or will you have to replace those with 10-rounders? Another consideration might be testing magazines for function with your gun and ammo, especially if you are required to make a change.
