Belton Flintlock (Wiki)[1777]
"The Belton flintlock was a repeating flintlock design using superposed loads, conceived by Philadelphia, Pennsylvania, resident Joseph Belton some time prior to 1777. The musket design was offered by Belton to the newly formed Continental Congress in 1777. Belton wrote that the musket could fire eight rounds with one loading,[1] and that he could support his claims "by experimental proof."[2] Belton failed to sell the musket to Congress, and later was unable to sell the design to the British Army a year after the American Revolution.[1] There are no records that indicate that the gun was ever supplied, and it is uncertain if or how exactly the Belton improvement operated.[2]"
Wiki - Belton flintlock - Wikipedia
WikiSource - Correspondence between John Belton and the Continental Congress - Wikisource, the free online library