Here is some info I dug up. Apparently, this was the type of rifle actually taken by L&C for the Corps of Discovery. Two or three of the sites have good photographs and they all show a nosecap.
Voyageur
HISTORICAL BACKGROUND:
The U.S. Contract Rifle, Pattern of 1792, was obtained for the federal government in two purchases by General Edward Hand, former commander of the Continental Rifle Regiment of 1776, and an officer of considerable frontier experience.
After their fabrication in Lancaster and York, Pennsylvania, Hand sent about 400 of the rifles to Cumberland, Maryland, to equip Major General Daniel Morgan's Virginia Riflemen during the Whiskey Rebellion of 1794. At the end of this short-lived uprising, the rifles were turned in and stored at the federal arsenal at New London, Virginia. In 1801 they were transferred to the new armory at Harpers Ferry.
In March 1803, Captain Meriwether Lewis, 1st U.S. Infantry, ordered fifteen rifles removed from stores at Harper Ferry and prepared for the upcoming voyage of discovery. Lewis specified that new locks be fitted to the rifles and that a number of interchangeable spare locks and components be produced. In addition, Lewis ordered that the rifles be equipped with swivels to accept the slings which he obtained in Philadelphia. This proved a practical adaptation for a long trek through unknown terrain.
Understandably, the new lock design was used on the prototype
1803 half-stock Harpers Ferry rifle ordered by Henry Dearborn just weeks after Lewis' rifles were readied for the "Corps of Discovery."
SPECIFICATIONS:
Per instructions of Secretary of War Henry Knox in 1792, and as modified by Meriwether Lewis in 1803.