While I have had rifles which would string shots (usually vertically), I never had a barrel which would walk as it heated. I also have never shot one which walked as it heated up except when it was a function of bedding. This includes some barrels which had to be straightened multiple times during the contouring process.
I had one rifle (a BRNO ZKK 600 in 30/06) which I had bedded full length. If I sat down and fired five shots, it would produce a decent group (1 to 1 1/2 moa). If I then walked up to the 100 yard board and put up a new target, then sat down and fired another group, the first shot would hit six inches high. Successive shots would hit progressively lower until, after four shots or so, the rifle would group at the original point of impact. If I then let the barrel cool completely, it would group at the original POI. Free floating the barrel cured this. I theorized that the barrel was warmer on the bottom and, hence, longer so it was bowed upward. Can't swear that was the case but it seemed to be. GD
