The Spencer was made by a different company than the Winchester, so I don't know that anyone moved the magazine from the butt to the barrel for that reason. The Spencer came out at about the beginning of the Civil War and the Henry Rifle at approximatly the same time.
I don't recall anyone having problems with the Spencer, but I do recall Benjamin Tyler Henry using a 1860 Henry Rifle in Winchester's firing range and having the magazine blow up due to a supposedly rimfire cartridge blowing up due to recoil. At that time the primer was basically applied to the base of the cartridge and the firing pin struck (in the Henry) opposing points on the rim, but the point of the round behind a cartridge in a tube mag had set off the primer in the gun Mr. Henry was using. From this experience he decided that the bullets should be flat-nosed and the round was named the ".44 Henry Flat."
Also, some 1866 models were later made in a centerfire round and sold primarily in South America.
Wish I could find myself an 1873 in .22. If I could find a Uberti in .22 I would be a little happy. Now I will have to make do with my Winchester 9422.