I took my family to the NRA range this evening and my boy shot for the first time. He put 5 of 6 rounds at 50 feet on target with my Colt AR. Not bad and he also took the test and got his range card too. Only 7 and who knows how far he can go?

3 times my AR did not feed the last round with 2 different magazines. The round just sat there on top of the mag loose. the bolt held opened too. I just tilted the gun down and it slid in the chamber and I fired it away. I made dam sure another round was not in the chamber but it was empty. I also only loaded 6 rounds each time so I knew my count. Total rounds fired was 40. Any suggestions would be appreciated.  

Quoted: The round just sat there on top of the mag loose. the bolt held opened too.

Last top round is getting danced out of the mag as the carrier moves back to eject the spent case, instead of being retained by the feed lips and picked up on the forward stroke.  Since the round is popped out of the mag, then this allows the mag follower to raise the bolt catch and stop the bolt  before it starts it's forward run (as if you had a empty mag).


This is a mag problem.  
What type of mags are you using, and what are their conditions?

They are new Pro Mag Blue steel 20 rds. Never had this problem but I never only loaded 3 & 6 rds at a time. The more I look at it I do think it is the mags. I will try my Colt, Cooper, USGI, and Orlite after a good cleaning. The bolt catch is working fine as i checked it after the previous post. Spring is strong and clean. Every few years I have it gone over by N Virginia Gun works and its due in again. Anything else you can recommend I have them look for will be appreciated. Lastly, my mags run the mill from junk to new. I do not like any of them and plan on getting the HK SA80 next month. After all this is my first baby. Thank again.

PS. I did read all the FAQs prior to posting and most FTF problems seem to be Mags. This the first time I had this problem in 14 years with this Colt.

They are new Pro Mag Blue steel 20 rds.

Ah-Ha...say no more.  ProMag bad.  USGI good.  

A little update here. The mags are the problem. You need to look real close but they are all slightly bent. Now the interesting part. I got a look at the HK SA80 mags at my gun smith's shop. He does a lot of work for the Federal agencies here and showed me how they fit compared to my cheap mags. He also recommended Labell over HK SA80s. He showed me the slight movement the HK mags have in a Colt and then how tight the Labells were (a new one I had). His recommendation is save your money and get USGI, Colt, or laBell. Thats all from here. happy shooting.