Enfield carbines are marvelous little guns, in my opinion, and just ooze history. This particular one is a Royal Irish Constabulary (RIC) carbine, 10,000 of which were converted from obsolete British military Lee Enfield and Lee Metford carbines in 1903 and 1904. Where the British carbines had full-length stocks, the RIC wanted to be able to mount bayonets (specifically, 1888 pattern Metford bayonets). To accommodate this, the carbines were modified with a sleeve to increase the muzzle to the proper diameter and a spliced wood section at the end of the stock to allow a bayonet lug nose cap - which had to be mounted lower than the carbine stock would normally fit.
The Enfield and Metford carbines had been deemed obsolete after the Boer War, when the British army standardized on the new short rifle (the SMLE) to replace both long rifles and carbines. The SMLE included many other changes from the carbine pattern guns, which had different safeties, dust covers on the bolts, 6-round magazines, no stripped clip guides, and sights similar to the earlier Martini-Henry pattern rifles. Finding intact carbines in the US is difficult, as there guns had long military careers and were often updated and modified many times.
Note that the RIC carbine is very similar to the New Zealand contract military carbines, and the two are best differentiated by the wood at the nose cap. The RIC guns have a spliced-in larger section, where the NZ carbines have a smooth taper to the nose. In addition, RIC carbines were made from both Metford and Enfield carbines - the Metfords had been built with sling bars in the side of the stocks, and retained these in their RIC configurations. Enfield carbines used sling swivels on the bottom of the stocks.
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