The data set Gun (MEMSS package) reports on the numbers of rounds fired per minute, by each of nine teams of gunners, each tested twice using each of two methods. In the nine teams, three were made of...

The data set Gun (MEMSS package) reports on the numbers of rounds fired per minute, by each of nine teams of gunners, each tested twice using each of two methods. In the nine teams, three were made of men with slight build, three with average, and three with heavy build. Is there a detectable difference, in number of rounds fired, between build type or between firing methods?

For improving the precision of results, which would be better – to double the number of teams, or to double the number of occasions (from 2 to 4) on which each team tests each method?