I've been having problems with one of my AR's.  After approximately 100 rounds, it just stops cycling.  It will fire the round, but will not cycle the next round.  It actually ejects the round, but it only ejects it about 1 or 2 feet away from the AR, instest of the usual, which is several feet to the 4 or five o'clock position.  This has happened on two consecutive days.

Yesterday when it happened, one of the magazines was getting a little gouged on the right lip.  Also, with the bolt locked to the rear, I put in a loaded magazine and released the bolt and it would not go all the way forward without using the forward assist.  I initially thought it was not lubed enough since I used Slip2000 for the first time and I tought that had something to do with it, but last night I used CLP and it was well lubed today.

I think I ruled out any mag issues since I have used the same mags for a while and it does it to all the magazines.  The AR was cleaned and lubed properly each time.  The upper is a a Stag upper and it is a couple of months old.  The Carrier is about 3 years old and has over 10,000 rounds through it and I check it and it looks good and the carrier key is on good.  The bolt is a year old and has almost 10,000 rounds through it and it also looks good.  I took the Troy Handguards off and checked the gas tube and gas block and they look good also, but I did not take them off.

Any sugestions before I send it out to get looked at?  I know I'm all over the place, but I never had any problems like this before.

Quoted: Rifle make/brand type, and what ammo being used?

Thanks for the help, but I already too care of it.

Care to share what the problem was in the event that anyone else has a similar symptom?

Tighten down the gas key screws on top of the carrier, they are loose.