Original Item: VERY FEW AVAILABLE. The original MkI Version of the Snider Breech block did not have any type of locking mechanism to prevent accidental opening of the Breech. As the Snider became more common in the field, the need for some type of lock became apparent, so the MkIII version of the Breech block featured a locking bolt on the rear of the block, which locked into the rear of the barrel. This is the thumb piece lever that retracts the locking bolt, allowing the breech to open.
Note: Fitting will almost always be required. These were originally fit by hand. There is unfortunately no way for us to guarantee a fit.