Simply Rugged Chesty Puller system
Diamond D guides Choice
7X Leather Chest Holster
Ringler Custom Leather Wyoming Combo Holster
I have the Ringler Wyoming Combo for my 7 1/2" SuperBlackhawk hunter and it is far and away the most comfortable chest type of rig I have carried. It actually carries a bit more like a bandolero or shoulder rig but is easy on, easy off and quick to adjust. In the pics on Von's site, it looks huge, but in real life it is much more compact that it appears. Take a look at this thread for some better pics of one being worn (
http://www.rugerforum.com/phpBB3/viewtopic.php?t=264382)
The chest type harnesses like the Simply Rugged and others work well and hold the gun in place but can be a bit of a PITA to put on and take off if you happen to have a heavy outer layer like a parka on. They also take more time to adjust when changing the amount of layers you have on. If they are not tight enough, the gun tends to flop around a bit.