First, the "6P199" marking is NOT a date.  It is Center Industries' CAGE (Commercial And Government Entity) code.  Anyone who supplies items to DOD must have a CAGE code, whether the item is toilet paper or M1 Abrams tanks.  Look at the Mag FAQ for CAGE codes for other manufacturers.

Second, the other stampings on the mags indicate the month and year of production.  Mags stamped 09/94 (September, 1994) or earlier are legal "pre-ban" mags.  Mags stamped 10/94 or later are restricted "post-ban" mags, and are illegal (potentially a felony) to possess if you're not an LEO, active military, or government official.

The question was regarding the fact that Center Industries was not properly compying with the law, which required them to mark their post-ban mags with a "For LEO/Government/Military/Export Use Only" warning.  Center made post-ban mags from 9/94 through sometime in 2000 without these markings.  Apparently, someone called BATF and asked if mags without this warning were okay, and was told that they WERE okay.

The problem is that this wasn't even released as a written BATF opinion, IIRC.  In the past, BATF has acknowledged that Center wasn't properly marking their mags, but wasn't overly concerned, because "they're still marked with a date, so we can tell which are legal pre-bans and which aren't."

Until a written opinion is released from the Chief of the Technology Branch that says that post-ban-dated-but-no-warning mags are legal, I'd consider them to be restricted.

If someone has a scan of a BATF opinion letter to the contrary, I'd be eager to see it.

-Troy

Answer: VERY few.

But, the price of suddenly finding yourself the subject of police scrutiny in this area is VERY HIGH.  And although this is rare, it can happen out of nowhere.

Witness the experience of one of our members, by the handle of "OneShotOneKill".  He had is CASED, POST-BAN AR in his trunk, and got a flat tire.  He had to remove his CASED gun from the trunk and set it by the side of the car in order to remove the spare tire and jack.  Some soccer mom called in a "man with an assault weapon" sighting on him, and police swarmed him, arrested him, and confiscated his gun and mags.  It cost him a considerable amount of money (enough to buy SEVERAL pre-ban ARs) in legal fees to deal with the incident, even though all gun-related charges were ultimately dropped.

It was still difficult to get his rifle back, and they looked for any excuse not to return it to him.  A single post-ban mag could easily have been the deciding factor.

Again, getting caught is unlikely, yes, but the penalties can be much higher than most people imagine.  Plan accordingly.

-Troy