Classic Science Fiction, alien planets, Hyper-drive space ships, contra-gravity, weird societies. For all that the characters are human and problems (I said Classic Science Fiction) are human problems. Neither of these stories have overlapping characters.

Four Day Planet is about a young man trying to be a reporter in a small town (the only town) on a back water planet. Oh, by the way, there are only 4 days in this planet's year. The year is about long as ours so as you can guess the conditions are rather extreme just as is the local wild life. As the story progresses we have graft, corruption, attempted murder, revolution, monsters and oh yes lots of guns. Did I mention Piper's universe is full of guns, regular fire arms that any old NRA member would recognize? The characters are well developed and well paced. I have read this one many times and enjoyed again and again.

Lone Star Planet - Pick a planet where the 'New Texans' packed up the Alamo and brought it with them and Piper will show you a planet that out Texas's Texas. Add in a deep streak of Libertarian government ( I think Piper was a Libertarian before the word was invented.) The main character is an Federation (Earth) Diplomat who has been issued a pair speed draw pistols as part of his Diplomatic Uniform and you'll see that is not a diplomatic mission you have ever seen the like of. The locals are ranchers who need armored cars and auto-0cannon to herd the local 'Steers' (big as a Mack truck and twice as mean as a Long Horn.' As usual Piper has good characters and a plot twist towards the end that makes satisfying reading.