I pulled this tid-bit from another site. Hope it sheds some light on the subject.
The Snider rifle was a .577 cal. breech loader, it was approved in 1866. The first Sniders were converted P/53 Enfield rifles.
This bullet is the Mark I Snider bullet, the complete cartridge shown here would be called Cartridge Ball Mark I. The word "Mark" replacing the word "Pattern" which is used on earlier British firearms and ammunition. The cartridge was designed by Col. Boxer and was approved for use in 1866. The Snider bullets can be found in Marks I - IX, the variations are not great, but they can have 3 or 4 cannelures (rings) a baked clay or solid iron cavity plug, and with the wooden pin or lead spun over nose cavity.
The purpose of the hollowed tip was to cause a more stable flight. The first (Mark I) bullets had a wooden pin inserted in the cavity as you can see in the picture in the original message above. Later versions still had the hollow tip, but it was spun over with lead and would look like a regular bullet. It was later found that these bullets inflicted serious wounds and use of the hollow tip bullets was discontinued for military use.
I guess this could represent one of the first hollow points even though the original intent was to improve ballistics, not to inflict a more serious wound on the enemy.
These are definitely NOT explosive bullets, I too have them sold as explosive. Once again, they come from Prince Edward Island Canada and England.