I have been toying around with my new TP9SFX regarding magazines. I was able to scare up a grand total of 7 in relatively no time at all (helps that I already had a SF :P ), but while I was looking at the 20 rounders and went, "Self, I've seen this before. That's the same extender that I have on my P226." I looked around and NOBODY, it seems, is willing to acknowledge the compatibility.

I have test fitted it and it does fit and take 20x 9mm, but I haven't test fired it yet. I haven't found any of the cheaper plastic ones to test (did not only find out that Mec Gar has metal ones but found some in stock), so right now the only way to test the theory is for me to cannibalize one of my P226 mags.

I don't realistically see a problem but you never know. Has anyone else tried it?

In my flurry of frenetic mag buying prior to the 10+ mag ban here in WA, I too found a batch of Canik 20 rounders and noticed the same thing about those bases. They appear to be identical to not only the P226's extended bases, but to the ones Mec-Gar has used on OE Beretta 92 extended magazines.

I'm pretty sure Mec-Gar is the OEM source for all three of these specific extended magazines, so it wouldn't surprise me that Mec-Gar could've reused the same base over and over again. But are the bases actually identical to one another regardless of platform and not tweaked in any way? That I don't know; I haven't pulled off any of the extended bases that I have and swapped them around to be sure.

Mec Gar is the OEM, per the side of my mag, and the P226 extension is definitely the Beretta extension.

I wonder if they can't acknowledge it for legal reasons.

My only real complaints are that 1) I'm having a hard time finding plastic extensions, and 2) if I want them to match my gun (I kinda do) I have to Cerakote them myself. I wonder if Canik USA's customer service could help me there…

They might have different springs …

I ended up buying a metal adapter base, so we're going to find out.

I know the P226 mags don't have different springs, and that I've got mags that I converted in 2010 to 20 rounders that are still going strong with the original springs. Since both mags come from the same vendor I suspect we'll see similar longevity from the Canik mag.

So an update for the interested. The aluminum adapter doesn't fit the Canik, however it was able to free up a plastic adapter and its base plate (they're different, but it's a couple of mm difference), which does fit flawlessly.