That is a Sharps 45-70 chamber it is not a Sharps .45 2-1/10 chamber.

They made both and they are very different. The 45 2-1/10 chamber has rifling to the very end of the chamber. There is a like new 74 here in town marked .45 2 1/10 and it has no lead, none.

Another friend in town has a Sharps 74 marked 45-70 and it is chambered for the groove diameter cartridge with a lead for using both commercial and government ammo.

MP Sadly Deceased as of 2/17/2014