I am of the bellief that a certain load will work better in a particular gun that others will, that is why I use them.
However, to roughen up a bore or intentionally pitting it to try and change the pattern is complete lunacy to me, and it's not the only things that has been professed in the past by people who knew no better or thought they did and could sell either an article to a magazine or something else they manufactured

How about shooting the gun with a load that works well with it to improve your scores?
THAT would be a bigger help than trying something that would ruin a bore and degrade a gun, but that's just my opinion.....
DT

Of course I have shot all my vintage guns - what do you think they are called SHOT guns for??!!