Am I correct that this age of P229 can use P228 Mec-Gar and Sig Sauer classic or original P229 9mm magazines reliably?

They seem to fit securely but I know there is a need to switch to E2 or something like that after a specific model year, I'm just not sure when.

How about a standard non rail P229, with a German frame, manufactured before 2004? Are they GTG too?

As an FYI, I have a Barsto conversion barrel.

Thx

Any P229 that will take a .40 or .357 magazine should ideally use P229-1 9mm magazines. The latter are the same width as the former. Anything else such as P228, P229 legacy magazines are slightly narrower and will have some wobble. It's extremely small but it's there.

Is that true for German made frames? I thought they changed up the frames when production started in the US or shortly after.

If I understand you correctly, you have a P229 in .40. Then it doesn't matter if the frame is German or US made. The internal magwell dimensions are the same. It uses the wide body mag, which is the same dimensions as the the 9mm 229-1 mag. You're going to use the 9mm conversion barrel to shoot 9mm, the correct mag is 229-1. You can also use the P228 mag, which is identical to the original P229 (9) mag, in this gun, but as said above, it will be just a little loose inside the magwell.

Now, if you're talking native 9mm P229s, that's when we have difference in the frame magwell dimensions.

Original P229 (9) has the smaller magwell than its bigger brother P229 (.40/.357), thus uses the same mag as the P228.

In the 2010 SHOT Show, SIG introduced the new E2 P226 and P229. The P226 is irrelevant to this discussion. The new P229 E2 (in 9mm) frame is now standardized with its bigger brother. Its magwell is now wider than the original P229 (9). So, SIG created a new mag to fit it and called it the 229-1 mag. And, at the risk of repetition, the old 9mm mag does work in this new frame, but it will be a little loose.

^^^^^
Thanks! Great explanations.