RickyB, When I was down at the PM Hunt, one of our sponsors was selling some 5 & 10 round AR mags there... I bought one, but haven't had a chance to try it out yet...due to crappy weather...
You might want to give them a call, as the magazine looks really good and fits well in all three of my receivers..not too tight, but no 'slop' either..
Specialized Dynamics,
www.specializeddynamics.com or give them a call at 480-968-2151 (AZ)
I'd let the know that you are a PM member and were referred by another...