How to access data in a JSON file using a factory and $http in AngularJS?

I am decently new to AngularJS, so apologies in advance is this is a basic solve. I want to be able to access and add to an external .json file using AngularJS. When I hard-code the data within a factory, it shows up fine. However, when I try to access the data using Angular's $http, nothing shows up.

Here is my factory:

sampleApp.factory('findSamplesFactory', function($http) {
    var samples = $http.get('sample.json').success(function(response) {
        return response;
    });

    var factory = {};
    factory.getSamples = function() {
        return samples;
    };
    factory.insertSamples = function(sampleNumber, sampleBox, sampleRow, sampleLevel) {
        samples.push({
            number: sampleNumber,
            box: sampleBox,
            row: sampleRow,
            level: sampleLevel
        });
    };

    return factory;
});

And here is the controller I have set up

sampleApp.controller('sampleAppController', function ($scope, findSamplesFactory) {
    $scope.samples = findSamplesFactory.getSamples();

    $scope.addSamples = function() {
        var sampleNumber = $scope.newSample.number;
        var sampleBox = $scope.newSample.box;
        var sampleRow = $scope.newSample.row;
        var sampleLevel = $scope.newSample.level
        findSamplesFactory.insertSamples(sampleNumber, sampleBox, sampleRow, sampleLevel);
        $scope.newSample.number = ' ';
        $scope.newSample.box = ' ';
        $scope.newSample.row = ' ';
        $scope.newSample.level = ' ';
    };
});

The .json file validates fine. Any help would be appreciated!

EDIT: Here is a Plunker of my full app: http://plnkr.co/edit/2itJiB?p=preview