Your observations are tracking along with mine. I'm thinking that the rougher bores attract and hold fouling more so and quicker than the mirror smooth ones and settle down much quicker. I have an old Savage 110FP 308W that I'll get rivers of blue from after as little as 20 rounds, but only requires a single fouling shot before it starts grouping into the high 2's to low 3's from a cold squeaky clean bore. My new Criterion 223R barrel on the M12 target action takes about 8- 10 before I see it settle down and start grouping again. In the short term, that factory 308 barrel is actually much more accurate than the lapped Criterion is, but only for about 40 shots before it is getting severely fouled. The smooth match barrel takes more shooting to get into prime, but will then stay there twice as long s the Savage barrel. So I'm still at a loss as to which is better. I am only a casual shooter so for me that old 308W barrel is better. If I needed to shoot 100 rounds accurately without cleaning I would need the lapped barrel. This hobby is an interesting one for sure.I have noticed something over the last few years. I have had NEW BBLs that "break in" in just a couple of shots. By "break in" I mean that I can clean them with just a couple of patches and get zero blue on the patches after sitting with copper remover . I have had tubes that take the whole 1 shot and clean for 5 shots, 4 shots and clean for 5 sets and then 6 shots and clean for a few cycles...up fo 40 - 50 rounds....and they still don't clean up like the "easy ones". Now....when it comes to a match, the ones that take all of the work to break in settle down after 1 shot....2 for sure and they are dead on. The tubes that started life so easy to break in and clean...some times it takes many shots to settle in....like up to 7 - 10 shots. I will be almost done with the 6 min sighter period before they settle in. Not sure if this makes sense or helps...but there it is.
Tod