I don't quite remember what the load was that shot well - as one barrel was wonderful with a certain load, but the other blew donuts with it.
Then, 3 or 4 different attempts, we found a combination that was equal, side to side and almost as good as the 'best' pattern.
When working with 2 different barrels, getting equal results is much harder. Perseverance pays off, after all, "We must endeavour to persevere".
A great man said that, or is said to have said that one.