I agree that the regiment was clearly raised in Louisiana in the Spring of 1862, organized and trained around Monroe and Delhi, and at least some units had a mixed record before joining the Vicksburg command. But their record thereafter was pretty impressive--Chickasaw Bluffs, where they helped stop Sherman's move up the Yazoo; Port Gibson where they went directly into battle with Grant's advance guard after an literal marathon march from Vicksburg, and held up the Union forces until other Confederates on their flank were forced to retreat, thus forcing their retirement; and after the defeats at Champions Hill and Black River they were chosen to serve as the rear guard for the entire army--a crucial role reflecting the reputation which Baldwin's Brigade (of which they were one of 3 regiments) had by then established.

If you read Baldwin's after acton report following the surrender at Vicksburg you will see he held Lt. Col Griffin of the 31st in the highest regard.