Some folks probably know more about that than me, but personally in centerfires I never clean between ammo types in the same gun. The only exception to that would be if I shot steel case ammo, which I never do anymore, I'd clean between switching. I've heard steel case ammo does not expand as much so it can create more carbon buildup in chambers, so then if you switch to brass you can get a stuck case. Of course I've also heard that's a myth. What I can say is when I've mixed the two in the same shooting session, pretty much always in AR's I've had problems, even in guns that run either ammo fine (as long as you don't mix them in the same session).
I do believe in rimfire guns, if you switch ammo, especially since some of them have drastically different bullet lube, that it can take a few rounds to have the barrel settle down with the new lube. One camp feels that a "strip to metal" cleaning is actually counter productive because it removes all the lube that has been "seasoned" in the barrel. Quite a few tend to advocate for cleaning just the chamber to remove any carbon fowling and basically leaving the rest of the barrel alone. The theory being that it helps even out MV etc.
Vudoo's recommended cleaning is similar, basically get the carbon out of the chamber and leave the rest of the barrel alone, he also states they believe it can take 1000 rounds to fully season a barrel for max performance. However one also has to remember the game, there are no sighters/fowlers allowed in PRS, like there is in say various benchrest competitions, so the gun has to perform first shot of the day.
That said, on some of the rimfire benchrest forums, it seems the vast majority say they do a full cleaning, every match, most appear to use brass brushes as well, and from what I've read most indicate that only a handful of rounds are needed to get back to max accuracy. Not saying either is right or wrong, but clearly benchrest demands more pure accuracy performance than PRS/NRL rimfire does.
I also thought it was interesting that several people on some of the benchrest forums reported boretech cleaners causing corrosion, we've seen Frank from Bartlein report that as well. In almost every case I read it seemed to result from people leaving the products in the barrel too long (after all boretech cleaners are water based, so it's not surprising they would cause corrosion if left)
At first I downplayed that concern because you just make sure you dry patch the barrel out. However, what I didn't think of that many brought up, is that the corrosion they ran into was not often in the barrel, but where the water based cleaner might seep to, for example back into the action, feed ramp, trigger, chamber etc. This could be a bigger concern in rimfire guns simply because the boreguide does not go into the chamber, so cleaning fluid can easily migrate down the chamber face and into the action. Where with most centerfire guides go into the chamber and often have o-ring seals. It also probably helps to make sure the barrel is angled downward a bit.
