I would examine the bayonet and try to find one that matches.
Measure the bore. Is it smooth or rifled? How long is the barrel? Note the shape of the buttplate ( I think the trigger tang is bent, but note it's length.) It seems to have only one barrel band (unless you didn't find the other/s) and a metal forend cap. Compare this data with rifles/ muskets you would expect to find at that location.
From the bend in the tang and the slight bend in the barrel in the same direction, I would say that it ended it's career wrapped around someones head in close combat.
The Bayonet type and action leads me to believe that it is a US Springfield. The picture of the breech isn't too clear, but it appears to have a nipple arrangemnt
I believe the key here will be to match the bayonet. There were slight differences for different models. The one pictured doesn't seem to match the Austrian rifle.
The buttplate looks too square to be a Springfield rifle, perhaps an Enfield or a Mississippi rifle, which had only one barrel band and a large intricate forend cap. It also had a patchbox, but that may have been eliminated when converted to fire Minnie balls, or just not found.
Found another photo of the 1854 Lorenze bayonet, it might be a better match than I first thought. The hammer shape also seems to fit the Lorenze.
I think the first step is to learn the history of the site, find out what units served there and how they were equipped. This will narrow the possibilities. Then match the characteristics of your find (bayonet, barrel length,) for a positive ID. Once you know what you're looking for, you may want to visit a museum for a close look at butplates, hammers, lockplates, bayonet sockets and blades.
OK, Here we go. After looking over a bunch of rifles, I found it to be possibly a Enfield Rifle.
J.S. Anchor- marked Enfield Artillary.
Imported from Great Britain est. 1861.
Later some of these rifles were converted to carbines and also barrels had 3 groove rifling added.
I hope this of some help. Being that it was found in Alabama, it told me that it was Confederate.
Looking at Confederate rifles used back then, this is what I found
One more thing I just found that the British wanted to stay neutral to the North and South, so they
contracted the manufacturing and shipping of these rifles out of England.
The Austrians sold a very large number of the Model 1854 Lorenz muskets to both the North and the South during the Civil war. Mostly they sold them in .54 caliber to the South,and in .58 caliber to the North. And they often used whatever surplus parts they could adapt to this model. So there are numerous variations seen in this model. I base my identification on the details of the hammer, profile of the lock especially the cutout for the nipple bolster, and the shape of the bolster itself. No American musket nor the Enfield muskets used this lock profile or this type of bolster. Almost any bayonet of the period could have been adapted to the Austrian musket. The user of that musket may have just picked one up and stuck it on.
Michael, remember that rifle was ruined by hitting someone on the head in violent combat. He held the rifle by the barrel and bent it on an opponents head, A special collectors item.