I found HK Magazines at a local store, the 12rd mag for a USPf .45 was only $44 which is very low compared to online and the fact that it was in a store in NJ where everything related to guns seems to cost more than other states.

The magazine looked just like the mags that came new with my USPf .45, except the mags for sale at the store did not have LEO restriction marked on them, the spot where that paragraph is normally written on the mag was just blank.  Everything else was the same, the floor plate and body markings.

There was no HK packaging for any of the mags, the man said that they get Glock and HK mags in bulk, the store just packages them up in ziplock bags with their own label.  

The other HK mags looked real, the mag for a P2000 had the LEO markings.

How do I tell it if is a genuine HK mag?
And if it doesn't have LEO markings, does that mean it's really new (did HK start making mags without LEO markings?), or really old (pre-ban?)?

Genuine HK mags have the HK logo on the bottom of the base plate.

www.ar15.com/forums/topic.html?b=5&f=29&t=28395

Quoted: Genuine HK mags have the HK logo on the bottom of the base plate.

Yes, it has it along with "USP".
The bottom of the metal magazine body says the caliber.

Does that mean it's a real mag?  No other brand marks their mags like that?  (I figured at least one other brand might have totally copied HK's design)

Is it a new mag made recently, or before the ban?

Thanks!

Quoted: www.ar15.com/forums/topic.html?b=5&f=29&t=28395

??

Sounds like a HK mag to me.  None of the recent made mags have the LEO markings on them; no need for that any more.  Many, but not all, pre-ban mags had date codes on the body, such as id, ir, is, or np.  If there is no date code on the body it is probably a recent post sunset magazine.  I have not seen date codes on mags since 2002 when the mag/frame codes became the same as the slide codes.
Compare quality.  If the mag in question looks the same as the known HK mags you can bet it is a HK mag.  Pro-Mags do not look identical to HK mags, at least not the ones I have seen.  I do not know of anyone else making aftermarket mags for HK USP/C.
I have a few positive HK mags with no HK markings on them at all except for the floor plate so the lack of markings on the body means nothing.