Just bought an SA-35 and I am interested in carrying it.  

It came with 1 15rd and I've ordered 3 more 15rd mecgars.  I've tried google but can only find references to people using these, not any for sale.  Any leads?

I don't think they exist.

Went to Mec-Gars website and they don't show.

The ORIGINAL Hi Power was a 9mm 13 round gun & most "Factory" Hi Power 9mm mags are 13 rounds.

Mec Gar made some +2 mags for Sig 226, S&W 5906 & Beretta M-9 / 92 which took these guns from 15 to 17 rounds.

I think the MecGar +2 is taking the High Power from 13 to 15 rounds.

https://mec-gar.com/product-category/magazines/browning/?attra-caliber=59

Bigger_Hammer

I believe that the flush fitting 17rd magazines are for the "new" 2022 FN Browning Hi-Power Series, and they don't fit in the original P35 series HP's like you currently own. Meg-Gar only makes the 10rd, 13rd & 15rd in flush fitting magazines. If you get lucky, you may run into some discontinued Meg-Gar 20rd magazines that hang out the bottom about 2". They are more reliable than the 15rd flat hollow base follower. I only use the 10rd, 13rd & 20rd when I break out a BHP.

Years ago there were South African (KRD) 17rd magazines for the Hi-Power. A bear to load 17 rounds in, unreliable, and known to split down the back spline when left fully loaded over-night. Avoid if you ever see them for sale. And they were not flush fit if my memory serves me correctly.

The Mec-Gar +2 baseplates will take a 15rd to 17rd, with some protrusion from the grip.  

https://mec-gar.com/shop/upgrade-parts/pads/plus-2-aluminum-for-metal-floorplate/

It's a shame that the new FN 17rd mags don't fit the older hi-powers, but I understand why they redesigned it.

Old school KNR marker Argentinian made mags were 15rd flush fits.

The 15 round mags are made by removing the 'legs' on the bottom of the standard 13 round mag follower.  There's probably not enough space in the grip for 17 rounds to fit and the magazine still be flush.  

jd1

I have about a dozen South African KRD 17 round mags. from 20+ years ago when CDNN was clearing them out for $5.  In the beginning, they are hard as hell to load 17 rounds but after several times they get easier.  I only use MecGar 13 rounds or 20  round mags for anything serious but I use KDR mags for practice.  I just load all dozen mags with 17 rounds at home and take them.  Despite using them for 20+ years, I never had a failure in my Mk II and MK III Brownings.

KRD.  Not sure why people keep saying they're South African; KRD is Argie.

The 15-rounders are not quite flush; they protrude just a tad.  I have one.  I also have a 17-rounder, which is like if you put a really thick base plate on the bottom of a flush-fit mag.