Heating a barrel can cause it to warp a bit, but even if it doesn't touch the barrel channel, the barrel whips when fired, so some heavier hunting calibers need at least 1/16" of clearance at all times. Most rifles don't have that much clearance from the factory, some are bearing at some point along the channel.
In this particular case; however, barrel fouling may be the culprit. Barrels are more likely to foul when new, especially if heated too much.
People are like rifles. Some are tried and true, having great eyes, personality, and fun to be with. Others never seem to hit the mark with you. Still others go off half-cocked. Still, it's nice to know most of them.