Concerning my newly purchased Remington 7400 in 30-06 (made in 2002):
Initially, the first 50 rounds produced jams every third round, so I went to work on it by bedding the action / stock / installing a LimbSaver Barrel De-Resonator / adjusting the trigger to 3 lbs., and dry-firing / working the action 1,000 times.
A major and very thorough cleaning of the action and chamber was performed. Did I say take your time and pay close attention to detail in cleaning the action / chamber / bolt?
Afterwards, the 7400 30-06 has not jammed in the last 200 rounds and is shooting groups that vary between 7/8" and 1 1/8" off a benchrest and 1 3/4" to 2" groups offhand - using 180-gr. Federal Solid Base rounds.
Speer Hot Core 165-gr. were slightly more accurate and shot the smaller groups, with the 180-gr.'s being the largest, but not my a large margin.
Will try some Nosler Ballistic Tips and AccuBonds next.
Steve
P.S. Groups definitely opened up when the barrel's hot, but no accuracy problems in firing a quick 4-round magazine from a cold barrel, as in the worst case hunting situation.