Well I just got back from the Ranch. I put about 300 rounds through my new magazines. They worked out very well.
I had one or two Failure to Fires but this may have been due to the fact I was using mixed ammo, I was using winchester 222 HP and Remington Golden Bullets HP. I had them mixed together in a bag so they were loaded just as they came out of the bag. My buddy put about 100 rounds of Winchester Super X HP through them as well. I think he had one failure to fire.
I think the failure to fires could have been the ammo or it could have been the fact we were testing out the Slide Fire system for the first time.
Eitherway overall I am a happy customer.
Only con is that these things are a PITA to load which we all know.