What you read was mostly incorrect. The reason for a first shot flyer, even in a quality match gun, is that the barrel is not seasoned or completely coated with wax/lube. Every top benchrest rimfire shooter I knew cleaned their barrel after every target ~ 40-50 shots. The reason for this is that it is easier to repeat a clean barrel condition than some varying degree of a dirty barrel condition. The lead/carbon ring build up in the leade is a problem, but regular cleaning with a brush keeps that at bay. That ring does not soften and will swag the bullet down in size, which we don't want. During a match I would put about 5 rounds down a clean barrel off target and off sighters, into the berm to thoroughly coat the bore with the wax/lube of the ammo that I was using that day. After that, I would go to my sighters to confirm consistent groups and to get a handle on the wind conditions. When everything was settled down and conditions were figured out, I would then go to my record targets. This is allowed in all the sanctioned rimfire events. Once a good barrel is properly conditioned with lube, the accuracy will be good up to and until the lead ring forms or until the barrel is too fouled. When that happens is a guess, which is why most would clean after every target and then shoot a couple foulers before going to the record targets. I know of no one in competition that used a fire lapping round. Our match barrels were perfectly lapped by our gunsmiths, no need to bugger that up. Just cleaning with a couple passes of a brass/bronze brush after every 40-50 shots is enough to keep that lead/carbon ring at bay. For the average non-match .22 rimfire, it's not an issue as they are not required or expected to shoot the .1-.2" groups that are expected from a match rimfire to be competitive.
My 541 THB will shoot a cold barrel flyer, then settle down. However, if left to cool, even after the barrel has been conditioned/fouled it will throw another big flyer. This is not typical or expected.
