Original Item: Very limited availability. When originally issued, the butt stock of the Lewis ground gun consisted only of a wooden stock, a butt plate with screws, and the butt cap with its screw. This was the Mark I. There was no provision for a sling, nor was there an oil bottle. In July, 1916, during the Battle of the Somme, the addition of a swivel and oiler was approved, creating the Mark I*. Six months later, in January of 1917, a reinforcing bracket was added to the butt cap. This was the final version and was called the Mark II. All models are very scarce.

The oiler is identical to the oilers in the spade grips of the Vickers machine gun. The only difference is that the Lewis adds a retaining ring to the bottom. An especially interesting feature of the Lewis is that patent information is displayed on some butt plates. The butt plates on the IMA stocks show the BSA information, which consists of a patent number and date, in two columns. (Guns made in the U.S. by Savage Arms display only the patent dates in one column.) The condition of all examples is in remarkably good condition, although most of the stocks need cleaning.