Big problem with Sig P229 22lr conversion kit

[senorgrand]

First off, I'm a total newb, but my uncle took me shooting recently and I caught the bug. Went to the range as soon as I could and rented a bunch of pistols and fell in love with the P229.

Bought a used P229 online and a new 22lr conversion kit and finally put them together last night.



Oh wait, something's wrong



What the what?!

Again, I'm a complete newb, but doesn't this seem like a p226 slide?

Take a look at it compared to the P229 slide:



The interesting thing is, the slide fits (mind the gap) and the action works. The clip also fits.

Now, I have three questions:

1) What is it that I have here?
2) Would it be safe to fire on my p229?
3) Whose fault is it?

Before you answer the last question, look at the front of the carton. Isn't that little box supposed to be checked at the factory?



I won't post the pic, but the back of the carton has the retailer's sticker which clearly labels this for the P229.

Help!

[senorgrand]

I cross-posted on the Sig forum and they confirmed that it's a 226 slide. I'm going to try and return it to Sig directly for a replacement that fits my p229.