no disrespect intended but my answers are a bit different. Rangers carried a variety of guns, some issued, some personal. They had plenty of latitude in what they were allowed to carry. Back in the 1930's, the Texas Highway Department bought 100 Govt. Model .45's, which were issued and I think that started the trend for Rangers to carry .45 autos.
The punchline to that story about carrying a "dangerous" .45, cocked and locked is "I wouldn't carry the sumbitch if it wasn't!"