I have the VP9 le and all three of my magazines rattle with my Gold Dots when fully loaded. All three everytime. They only rattle when they are not in the gun. When inserted in the pistol they no longer rattle. None of my 3 sig magazine or 11 CZ magazines rattle. I don't think they should rattle and understand the OP frustration but I don't lose any sleep over it. My VP9 has been 100% reliable and fun to shoot.
My mags rattle a bit also. They don't in the gun, but if I eject a full one it will rattle a bit. A couple of raps on it will usually settle things out and it will stop. I've noticed it a lot more with my JHP defensive rounds loaded.
After loading mags, give a good smack to the bottom (hold your thumb over top round to prevent it from flying out), to let rounds rearrange inside mags and no more rattling. If you do not feel top round going down into mag a little, then smack is not strong enough. Worked every time for my HK mags (and STI mags as well).
I imagine the accumulated tolerances of 15 rounds of 9mm stacked in a pistol magazine can vary to a great degree.
I've noticed the rattle in several mags across several manufactures and even different types of firearms. What I have concluded is it is caused by drag on the casings against the inside of the mags and each other. The drag allows some of the rounds to load up against the mag walls and create a few thousands of space for one or two cartridges to slide forward and back. It is not a functional issue although I agree it can be annoying. It can usually be cured by fully loading the mag and then taping the bottom of the mag against a solid surface a few times to settle the rounds.
MP5SD SW clone SBR with TPM SD can
MP5 Coharie clone SBR with AAC Striker II can
MP5-40 Vector clone SBR
HK45 with Sico Osprey 45 can
Many Many more non HK firearms
Hmmm... I got into the habit of always rapping the butt plates of magazines on the palm of my hand years ago, just for the fact it helps "settle" the rounds. I've never noticed any ammo rattling before...maybe I'll pay more attention. Even with old warn out well-abused magazines, I never noticed it and have never had a fail-to-feed from a mag. Now I'll be hearing rattling rounds all the time! Thanks a lot!!
This got me curious, so I checked few mags I have loaded with EDC rounds (GoldDots and HSTs) if I shake them kind of hard I guess I hear a little rattle but had to shake pretty vigorously.
Then I tried shaking one of my PPQ mags loaded with 15 (of 17 max) Winchester rangers, sounded like a baby rattle.
In either case, have to shake pretty hard to get rattle sound, but the Walther Mec-Gar made ones are far noisier than the HK.
I have 10 mags for my P30 and the all rattle when I fist load them. I tap the bottom of the mag against my hand a few times and its stops. I have 1200 rounds through the gun using all 10 mags each range session and the only time it has had any problems was when I was teaching my sister how to shot and she was limp wristing the gun to an absurd point that I don't think I could recreate if I wanted to. So unless you have the wrist strength of a 98lb 19 year old girl, I think you will be ok.