I was breaking in a new rifle the other day when I ran into a peculiar problem. Upon receiving the rifle, I checked it out thoroughly making sure that everything is properly staked and lubed. I then brought the unit to the range and started shooting it. All was well until I got to approx. round no. 90 (into the 4th mag). The gun started jamming. The spent shell stayed in the barrel. This happened 3 times before I realized that the barrels throat was caked up with carbon. I proceeded to field strip the gun and saw that my bolt was unusually caked up with carbon. The bolt gas rings were glued together by the build up. I had to use a blade to remove the carbon from the bolt. I'm aware that this happens but not after 90 rounds.
Could there be something wrong with the ammo I was using? The ammo was Armscor .223 by the way. Sorry no pics. Any suggestions?

