The new game mode "turned" is a nice concept but has a lot of work to make it a good fair match.
EX. the speed of zombies( fast) and the speed of gun change(slow).
But here iam just gonna tell you how to get a party of 4people(including you) into a public match which will count on your leaderboard.
1st. get into a party of 3 other people and including yourself it will be 4. be ready to invite them all by going to your menu and "invite party to game"
2nd, set your connections to BEST, as it will look for the best connection.
3rd. now quickly as it is looking for the best connection game send the invite to game to you party and that should be it.
putting the connection to best will give you enough time to get all 3 people in.