Chambers vary. Also, throats, and the lengths of throats, vary. In general (not specific to the Henry) the bullet nose profile can make the difference there, as can the bullet diameter. Lead bullets are typically oversized, and it is sometimes possible for an oversized bullet to stick in the rifling in front of a short throat, causing hard chambering as the bullet is being forced into the rifling. I've seen it happen.
I've also had a full-length-sized case stick HARD in a factory chamber. Trying the empty, sized case to see how easy it chambers, in the actual firearm, would be a good idea too, as part of the process of elimination.
Look very closely for marks on the bullet of a round that's been chambered fully and then removed without firing-- Look for tiny marks where it may have contacted the bore of the rifle in front of the throat. Also look for rub marks on the outside of the case near the mount, where an over-sized bullet may have expanded the case far enough to stick in the chamber.
Testing in a case gauge is fine and all, but testing in the actual firearm is the ultimate test.
So here's another thing that can happen. You can carefully slug a rifle's bore, and carefully size your lead bullets to one thousantch, or two, or three thousandths over groove diameter. Then you may need to use an "M" die to provide extra expansion of the case mouth so the bullet will seat in the case without shaving lead or some such. All that may be spot on and correct for your rifle's bore, BUT the now larger diameter case, which accommodates the properly over-sized bullet, may stick in the chamber.
I've had all these things happen in various firearms. I seem to be some kind of "magnet" for these irritating, freak problems when it comes to reloading.
Usually a very careful, visual inspection of the previously chambered cartridge will reveal the zone of interference. If not, paint the cartridge and the exposed bullet nose using a felt-tipped pen such as a Sharpie, and do it again, then look for odd wear marks in the ink.
