The formula for nearly every Hopalong Cassidy film is that Hoppy be accompanied by two sidekicks....and old cuss and a young handsome guy. Originally, the old cuss was Windy, played by George 'Gabby' Hayes. But after a contract dispute with Paramount, Hayes went on to Republic Studios...where he became the regular sidekick for Roy Rogers and also played second fiddle to a few others. This means that they needed a new old geezer...and they experimented with a few until they ultimately settled on Andy Clyde, who played 'California' is more than half the Cassidy films. In "Cassidy of Bar 20", the studio experimented with a new guy....Frank Darien as 'Pappy'. He wasn't bad but didn't distinguish himself...so Paramount kept trying.
The plot to "Cassidy of Bar 20" is pretty typical...a baddie, Clay Allison, wants to control everything and is trying to drive poor Nora and her outfit out of business. What made this a bit different is that long ago, Nora and Hoppy were a number...which is surprising for the normally asexual cowboy. In his films, he nearly always left the loving to his young sidekick, Lucky or Jimmy or whoever.
So is this any good? Yes. But it really isn't that special and there are several logical problems with the script. Worth seeing but not especially memorable.