The Henry
The Henry replicas are an authentic copy of the originals in all respects, to the best of my knowledge and according to my reference books.
The "distinct separate piece at the muzzle" you are referring to is the side-swinging nose cap where the brass follower pushes the mag spring, compressing it.
The barrel muzzle end is indeed round for the length of the nose cap assembly.
Watch "Dances With Wolves" and see Kostner waving his Henry around with the follower clearly visible at the bottom of the magazine, indicating that it is unloaded. This is the piece which causes detonations if carelessly allowed to drop on top of loaded rounds.
I don't recall if the movie makers of "Lonesome Dove" spared Capt. Call and Gus this embarrassment.
Now, the mag follower, the main fault of the Henry. It's a heavy chunk of brass.
On one occasion, I had supervised the loading of a Henry with 10 rds. The shooter snapped the nose cap shut as he laid the rifle on the bench, detonating three rounds. His wrist was shot full of fragments and the mag tube splayed open like a banana.
On the second occasion, the shooter dropped 5 rds into the mag during a stage and slapped shut the nose cap, sending it down the tube like a runaway elevator. Again, three rds detonated, but the blast went down range as he had the butt on the ground during the reloading.
The mag tube was similarly splayed. I found out later that it can be restored by careful hammering around a mandrel.
In both cases, an ammo check revealed NO high primers in remaining rds., all loaded with RNFP bullets. Henry users are advised to shoot hard shell primers.
Such detonations were also known in the era of the .44 Henry rimfire due to the sensitivity of the fulminate priming compound.
The follower also gets shooters into trouble when they stop it with their hands, thereby preventing feeding. One learns to move one's hand or arch the support hand to allow it's passage.
After the Civil War, the Henry patent rights were purchased by a consortium, the main principle being Oliver Winchester, a Connecticut shirt maker. He retained Benjamin Tyler Henry, hired mechanic Nelson King and set them to work on the first rifle to bear the Winchester name - the '66.
This was marketed as "The Improved Henry", which is what it was, taking advantage of the established reputation of the Henry. Improvements were the tube magazine common to all lever actions thereafter and the King side loading gate in the receiver, also part of every lever action rifle since.
It all other respects, it was a Henry, including the Henry .44 Flat cartridge chambering. The iron framed successor of the '66, the '73, was chambered in the centre fire .44 WCF, known today as the .44-40.
Winchester honoured Henry by stamping the 'H' head stamp on their .22 ammo for years. They may still be doing so.
The open mag tube may let in foreign matter, but it has the advantage of also letting it out! I got my '66 wet in a down pour and it was a bugger to dry the mag tube, requiring a screw driver to remove the end cap.
With a Henry, you would simply have drawn up the spring into the nose cap and wiped out the water with your shirt tail or bandana. A trained soldier always knows how to service his rifle in the field and get around it's deficiencies.
Sharps rifle shooters were known to pour water on a fouling seized breechblock or urinate on it. Must have taken a cool soldier to make water in the heat of combat!