First thing's first..... I LOVE my Runners Kit Bag. It is EXACTLY what I've been looking for.
I bought it expressly for the purpose of carrying my handgun while running. So I tried out the Vanguard idea, but I found that the pistol bounced around too much for my liking, even if I secured the Kydex tightly to the dummy loop. I noticed that bag came with the soft side of velcro installed, so that got me thinking.....
I basically made a 'half-holster' from .08" Kydex, installed a single eyelet (.25"), and attached the rough side of some heavy duty velcro to the back of the kydex. Through the eyelet I looped some 550 cord as a backup in case the velcro breaks loose during drawing the gun.
The gun now stays securely in place without bouncing while I run. I also made sure the gun is at the correct angle to draw quickly and comfortably if needed.
Here are some pics with my M&P Shield 9mm........ and if anyone has suggestions, I'm all ears. Thanks guys for a great product!!