The CSA government made hardee's revised manual the official one to use by all their forces.
But they didn't back that decision up with any money.
So we generally have no clear date for when specific unit changed books.
(VMI changed in 1864 and used it when they went into battle)
NC on the other hand did this properly.
They spend money on printing books and issuing them to their regiments.
So yes, you can generally expect that NC regiments did use Hardee's revised. From a point some time after they started to issue the manual.
And yes, there are some very clear differences in the manual of arms.
The manual in his 1855 book used the manual of arms for rifles. That is suppose to be used with short rifles, not longer muskets.
Since most soldiers where armed with a musket length weapon, he revised the manual of arms by taking hte positions from the manual of arms for muskets. So position of the musket during the first part of load and fix bayonets is different.
Instead of having it in front of you between the legs you have it on the outside of your left leg tilted forward.
This lower the height of the muzzle.
For me personally it make little difference, since Iam 182cm tall. But for a guy who is only maybe 160cm it make a huge difference. (I don't know the average height of the civil war soldier. But we know for a fact that the average in the danish army in 1864 was 166cm)
We tried it at one of our drill days and one of our short guys loved this version... but unfortunately for him, we are a union group.
If you want an easy comparison compare the two Silas Tackitt's booklets:
http://www.zipcon.net/~silas/Drill/HardeeRevisedBooklet.htm
http://www.zipcon.net/~silas/Drill/RifleBooklet.htm
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As I wrote in Facebook when a question about hardee's came up a few days ago:
More generally I would suggest reenactments units:
- Virginia units use Gilhams for early war and Hardee's revised for late war.
- Other CSA units in the east, use hardee's 1855 and then his revised.
(With NC units making the change earlier)
- Units in the west use Hardee's revised for most of the war. (since he served out west and was their "drill master")
The union used US. infantry tactics 1861. (that is Hardee's 1855 with a new cover and both the rifle manual of arms and the musket manual of arms, so depend on what arms they where issued) until a few month after Caseys' was published.
And then obviously do differently is there are sources that say so.
One example is the Wisconsin regiments. (2nd, 5th, 6th regiment for certain) used "Chandlers", and it is documented that the Iron brigade used at least some parts of his manual of arms trueout the war. (their temporary brigade commander in early 1864 complain about them not using Casey's for fixing bayonets)