Our hunting camp has had a 740 rifle around for over 40 years and a 742 carbine around for over 30 years, both are .30-06's. The only time any major jams occurred was in cold weather with too much heavy oil. The 740 rifle started showing point of impact changes if you went through 40 rounds in less than a half hour. (Not a problem for hunting, of course.)
The fellow with the 740 recently bought a 750 rifle in .270. He only shoots factory ammunition (quit handloading years ago). Federal Premium 150's shoot very well, I saw some groups in a 30 mph cross wind that were 2 inches.
He does have one "abnormality" though. When shooting from a bench, or offhand, or any field position for that matter, point of impact is consistent. As soon as he takes a half-turn of the sling around his forearm, his point of impact drops 12"-18"!! He has tested this in all the same positions in which he did NOT use a sling, and the results were conclusive.
Has anybody else seen this?