Generally speaking, the answer is, you can't. In the U.S. there is no national registration, and only a few states require registration, so it probably isn't registered. In the few states that require registration, the information isn't available to the general public.
The short answer is, you can't. Most states in the U.S. don't require registration, and in the few that do, the information isn't normally available to the general public. If you have a gun that you don't know who it belongs to, you may want to turn it in to the police, just in case it's stolen.
50-400 usd
Sig Sauer P229 and P239 chambered in .40 S&W. Here's the press release from Sig.
You posted the question under computer terminology, but I'm going to assume by Sig P228, you're referring to the handgun. The P228 was discontinued was because the P229 was a more popular seller, and after the P229 became available in 9mm, there was to particular reason to continue selling the P228. Additionally, the P229 frame is milled from steel, making it a little sturdier than the P228, which was a stamped frame, which is probably at least part of the reason the P229 was more popular.
You will have to call SIG to find out
You must contact SIG to find out.
You should go with the SIG P226 or SIG P229, both are really good in many catagories for combat, and since they can come in a .40 that's a vey nice thing too.
You will need to call SIG to find out.
SiG P229 in 357
you must call SIG to find out.
Yes same frame and assembly they will interchange
No. You can get a Sig P229 that will fire .357 Sig, but that is not the same as .357 magnum.