"Captain Richard M. Boone, commander of the 2nd Field Battery, Louisiana Light Artillery."

Light Artillery USUALLY is not equiped with guns larger than 12 Pounds which had 4.65 inches diameter bore which is a might skinned leg. And if you do not ram the leg all the way down the barrel it would act as a plug in the muzzle and cause the gun to blow up.

I am not saying that these artillerymen were not servicing one of the larger weapons at Port Hudson, but "2nd Field Battery, Louisiana Light Artillery" isn't the normal designation for a heavy battery crew.