As I recall, the original Henry rifles were chambered in the 44 Henry rimfire. One reviewer suggested they should have chambered the new "original" Henry in 44 Russian, a similar sized cartridge to the 44 Henry rimfire. That or the 44 Special, then the bore size would be correct.
They could have just kept it as a rimfire and Winchester could make the ammo for it. But I doubt that would be a profitable gamble.
Howdy Again
Left to right in this photo, the cartridges are 44-40, 44 Henry Rimfire, 44 S&W American, 44 Russian, 44 Colt, 44 Special, and 45 Colt. In the black powder era all cartridges were completely filled with Black Powder, so a good comparison can be made of the relative power of each cartridge just by comparing their sizes.
The Henry cartridge pictured is the original Henry Flat with a flat nosed bullet. The bullet weighed 200 grains, the powder charge was 26 or 28 grains of Black Powder. This cartridge achieved a muzzle velocity of 1125 fps out of the 24" barrel of the Henry rifle. Later a pointed 216 grain bullet was used for better ballistic coefficient and slightly lower velocity.
The 44-40 cartridge nominally contained 40 grains of Black Powder under a 200 grain bullet. Muzzle velocity out of a 24" rifle barrel was 1245 fps.
Notice the Henry cartridge has a copper case, not brass. This is mostly because the rim had to be soft to be crushed to ignite the priming compound. The Henry rifle (as well as the Winchester Model 1866) had a forked firing pin that struck the rim in two places 180 degrees apart, to increase the probability the priming compound would ignite. That is about as powerful as a rimfire cartridge could be, since the case had to be soft enough so the rim could be crushed and to ignite the priming compound. That is why the 44-40 had a brass case and Boxer priming, to accommodate the larger powder charge.
I hear guys complaining all the time on the SASS Wire about the current Henry replicas not being chambered for the original 44 Rimfire round, or a similar short round such as 44 Russian or 44 Special.
Good luck getting somebody to produce a 44 Rimfire round today. I have a box of 41 Rimfire derringer ammo produced by Navy Arms a long time ago. They are collectors items. I am not aware of anybody else producing large caliber rimfire ammunition today, there simply is no market for it.
As for 44 Russian or 44 Special, there are aftermarket parts that can be fitted to the Uberti Henry rifles so they can shoot those rounds. Personally, I could not care less. I am very happy with my 44-40 Iron Framed Henry.
Uberti produces their version of the Henry chambered for 45 Colt and 44-40 as does Henry Repeating Arms. Personally I believe they both made the right choice, choosing cartridges that are readily available many places. Try finding 44 Russian on a shelf sometime. Even 44 Special is harder to find than 44 Mag.
Other than some proof rounds at a government proof house, my Henry has never had any Smokeless powder run through it, only Black Powder. My charge is about 35 grains of Schuetzen FFg under a 200 grain bullet, because modern solid head brass does not have as much powder capacity as the old balloon head brass. Even so, 35 grains is plenty for me. I have no need or desire to be shooting more 'historically correct' ammo in my Henry. Yes, I could stuff more rounds in the magazine if they were shorter, but I can load 13 44-40 rounds on Sunday and shoot all week long as it is.
P.S. VERY IMPORTANT: When loading a Henry, do not hold the rifle vertically and drop rounds down the magazine as can be seen in some videos. DO NOT DO THIS! Also, be sure you have a firm grasp on the follower. DO NOT ALLOW IT TO SLAM DOWN ON A COLUMN OF CARTRIDGES IN THE MAGAZINE! CARTRIDGES HAVE BEEN KNOWN TO FIRE IN THE MAGAZINE! Don't tell me how it is not possible because of flat nosed bullets. Just don't tell me that because it has been known to happen. I always load my Henry by laying it flat on the loading table at a slight angle and I allow the rounds to trickle down the magazine. Then I carefully lower the follower onto the stack of rounds. Be careful if you have sweaty hands, do not allow the follower to slip from your grasp!