The Lancaster Rifle, Long Rifle (3 Band ) Short Rifle (2 Band) and Artillery Carbine were all converted to the Snider system. This means that there are a number of differing barrel length that will be encountered.
31.5 ins, 39 ins and 24 ins to be exact.
After 1869 as all old muzzloading weapons were used up, a further improved Model , the Mk III was put into production, and on this new model the barrel was shortened to 31ins. The MkIII is a much improved version having the addition of a locking latch applied to the breech mechanism.
Apparently, four models of the Snider Enfield were issued to Canada. They were the Long Rifle, the Short Rifle, the Artillery Carbine and the Cavalry carbine. The Cavalry Carbine had a 19 in barrel and no provision for a bayonet (not much need on a horse really!) It also has no forend cap and a short forend stock giving it the appearance of a somewhat "sporterised" carbine. This was the weapon issued to the North West Mounted Police when they were formed up in 1873.
This is a short version of its history in particular to the differing Marks and Models, but i hope you find it useful.