You might look at the Bianchi Carry Lok line, they incorporate a really nice quick release lock system. Your gun simply will not leap out, even if you stood on your head. Try the Carry Lok model 82
82 *CarryLok™
"http://www.bianchi-intl.com/product/Prod.php?TxtModelID=82"
If you like them, Midway USA
MidwayUSA — Shooting Supplies, Reloading, Gunsmithing, Ammunition, Gun Parts & Rifle Scopes "http://www.midwayusa.com" has the whole product line.