They're the same guns from the original painting. The Louvre gives the musket as "infantry gun with bayonet (1816 model)" - possibly this French Model 1816 St. Etienne Garde du Corps d’Roi Flintlock Musket and the pistols as "cavalry pistols" which could be anything. I didn't add a tag for the musket as I couldn't positively confirm the model and it would never be used again anyway.
Illustrated by: Kiryuu TakahisaClash! The Glamorous Tank Corps of High School GirlsWeekly GuP Manga