Ruger SP101 2.25" vs the 3 1/16" barrel; .357magnum...
IMO; for target/marksmanship, I'd get a Ruger .357magnum in a 3 1/16" barrel, then get top custom shop; Gemini Customs to convert it to DAO, Hybra-Port the barrel & tune it up, .
Massad Ayoob, sworn LE officer & gun writer put out a few articles in the 1990s/1980s about how 3" revolver barrels were popular with big city police detectives over the snub 2" but the 2" styles were more portable, concealed better.
The added weight & frame of the robust Ruger SP101 makes the 3 1/16th inch model a slightly better pick but with the DAO .357, the factory stock Ruger SP101 .357(with a factory .38spl +P or +P+ load) can offer the best of all factors.