Looking for a little knowledge...

I recently purchased a new Gen 3 G19, but wanted some additional magazines.  I found the best price at Natchez Shooter Supply, and ordered some.  They arrived today, and as expected are actually Gen 4 magazines, which is obviously not a problem, but there were two different kinds of magazines in the box.  None were in retail packaging, which is also not a problem, but I have a question about the differences.

Both types of magazines that I received have notches on both sides, but some do not have metal showing in the notch, nor do they have the notch on the front.  I also noticed that the font that "9mm" is in on the back of the magazine is different, as well as the fact that under the Glock logo on the back, the "normal" ones show Austria, and the others show 1594-01.

I have no concerns about using these magazines, or whether they are genuine Glock parts, but I'm just curious if anyone knows the real story behind the differences.

Here are pics:

I got three of those mags with my new G19 Gen4.

I like 'em.  The square cut out on the front was introduced around '07 or '08 for an ambidextrous mag catch that never happened.  The cut out on the other side was to allow the mag catch to be swapped to the other side.

These new mags finally look like they were made right the first time and not a chopped up Gen3 mag....

Ok....thanks for that info.  So maybe these with out the front notch and the metal showing in the left side notch are a new iteration of Gen 4 magazines.

For sure.  They're the newest.  My test fore date was the middle of January '15.

Bottom pic. Is that a crack from the "13" witness hole?

Just a scratch...and somehow it shows up more in the pic than it does on the mag itself. I had to really look to see it.  Must have been the lighting.

Just bought a G19.4 this morning and the mags that came with it were stamped 1594-01. The two extra Gen 4 mags I bought simply had the Glock logo. The born on date of the G19.4 is 01/31/15.

Just wanted to chime in. I was at a local gunshow today (take it for what it's worth). There was a guy selling OEM Glock mags for $15. He said he got a steal on them because Glock is moving more and more (maybe all) mag production to the USA. The mags with Austria at the bottom are obviously made in Austria, but he said the serial numbered mags denoted USA manufacture. Don't know  if it's true or not. AsI said, I just heard it at a gunshow. I bought 2 G17 mags and 4 G21's with a Glock pistol bag for $90. Best deal of any gunshow in a long time, for me.