also an aside it the P226 clips fit as well but they stick out of the butt of the gun approx 1/2 inch. it may be helpful if you want some older hicap mags to playwith.
someone else jump in if they have had a problem with the P226 clips in a P229
Yes they are basically the same mag. Guys who sell clips at gunshows will look all glassy eyed at you and want to sell you a 229 in 9 for a higher price(if they have any!) and will mumble about the 228 mag.
The SIG229 in 9mm is a very very nice shooting pistol!