I've found that most "Tactical Slings" are some variation of the HK sling. The Giles sling that Jeff Thomas recommends os very good. I have one and used it for years. I now use the sling made by Tactical Taylor almost exclusively.
It's like the Giles only it's made from 1 1/4" webbing and has a fastex buckle so that you can get it on and off easier. If you have an M4 type side sling adapter on your shorty AR you can buy their M4 model that will use the side sling adapter for the front attachment and not wrap around the handguard. They can usually be bought at a better price then the Giles sling too.