One other overlooked aspect is the period of time in which the barrel stabilizes. Now donít read more into this than what Iím saying. But letís say you load 75 cartridges exactly the same and fire them through a new bore. At the same time you did a few shoot and clean, and the barrel is cleaning up easily. You will notice that the velocity readings of these 75 bullets may be a little erratic, and will most likely increase through this period of use. After the 60th or so bullet the velocity readings should equalize and may be up to 50 fps faster than the first 20-40 bullets. This was not my finding, but pointed out to me by a friend who has broken in many more barrels than I have. Since that time I have seen it enough to believe it.
My procedure is exactly this: Shoot one round, remove all copper, one dry patch, one wet patch of Kroil, one dry patch, repeat about 5 times total. Shoot 5 rounds, remove all copper, one dry patch, one wet patch of Kroil, one dry patch. At this point 95% of the barrels I use will be cleaning up extremely quickly and easily, and I will begin some form of load development. I will usually try and get another 2 cleanings in the next 50 rounds or so, and monitor the progress with the bore scope. After this I consider cleaning to be routine and will follow the advice in the second paragraph below.
So this gets us to what should we be cleaning with? I use and highly recommend Bore Tech Eliminator. Itís a safe cleaner with no ammonia, and can be left in the bore indefinitely. Eliminator emulsifies the copper and suspends it into the liquid. It is aggressive enough that your brass jag alone will stain a patch blue. Now, I personally cringe at the thought of running a bronze brush down the bore of a brand new barrel, and I do avoid this. Repeated wet patches every 10 minutes or so will clean the barrel. Some stubborn barrels may get a couple of passes with a wet brush, but I prefer to let the Eliminator do its job.
A word on ammonia based cleaners, I cannot say with any certainty that ammonia if used properly will hurt your bore. But I have read that ammonia left in a barrel to dry can attract moisture, which may in turn damage the bore. So if you insist on using up your last bottle of CR-10, neutralize the bore with a few patches of darn near anything that will wipe out the remnants. Abrasive paste of any kind for the most part should be AVOIDED; Iíll talk more about this later.
Routine Cleanings After Break-In
At this point we are using our finely tuned machine to its full potential. With solid load data and drops worked out, we are enjoying the performance of our rifles. So how often should we clean that rifle? Easy. Before long term storage, or when accuracy starts to fall off. Thatís the simple answer. If you clean after 25 rounds because thatís what ďOne Hole JoeĒ told you to do, youíre most likely cleaning way too often. I have the pleasure of owning a couple of rifles that refused to foul their undies, so to speak. They shoot more rounds than I care to reload in a day without any excuses. Not all barrels will treat their owners this good, but if you have the pleasure, never do anything to that barrel that will jeopardize the internal surface finish. (I think Jim is talking about abrasive paste again.) Good thinking!