ASP.NET API Controller POST/Redirect/Get - angularjs

Question

I would like to use the P/R/G design with this API, using AngularJS on the client side. Here is my API method:
[HttpPost]
public HttpResponseMessage UpdateRaw(HttpRequestMessage request)
{
//do stuff...
var res = request.CreateResponse(HttpStatusCode.Redirect);
var authority = request.RequestUri.Authority;
var uri = string.Concat(authority, "/api/DataApi/GetRaw");
res.Headers.Location = new Uri(uri);
res.Headers.Add("Access-Control-Allow-Origin", "*");
return res;
}
I have another method in this controller (DataApiController) which is called GetRaw(). Basically I want the client to issue a POST, call this method, then get redirected to the GET method. Here is my JS code:
//get the data and build the js rep
$http({
method: 'POST',
url: '/api/DataApi/UpdateRaw',
headers: {
'Content-Type': undefined
},
data: {
test: "test"
}
}).then(function (result) {
console.log("RAW--------------");
console.log(result.data);
// do stuff...
}, function () { console.log("DIDN'T WORK"); });
When I issue the POST, however, my browser console says "The request was redirected to a URL ('localhost:25498/api/DataApi/GetRaw') which has a disallowed scheme for cross-origin requests." I am aware of this answer, but that had the same result.
I found another website somewhere which suggested adding the line
res.Headers.Add("Access-Control-Allow-Origin", "*");
but that does not seem to work either.
I am new to ASP.NET and Web Dev in general, so any ideas would be appreciated. Thanks.