Excel Accelerator MR-5.7 5.7x28mm, 18" Bull Fluted Barrel, RH, Black, 9rd. https://www.impactguns.com/semi-automatic-rifles/excel-accelerator-mr-5-7-5-7x28mm-18-bull-fluted-barrel-rh-black-9rd-810760011075-ea57101. 

OFFER IS FOR RIFLE, BUT WITH OUT STOCK AND MAGAZINE.WE HAD FIRE IN STORE AND STACK WAS MELTED DOWN.MAGAZINE WAS MISSPLACED .OFER JUST FOR WHAT YOU SEE ON PHOTOS.

https://www.classicfirearms.com/excel-ea57101-accelerator-rifle-mr-57-semi-auto-57mmx28mm/. 

MANY COMPANIES USED TO SELL THIS RIFLE AND PISTOLS BY EXCEL ARMS , LOOKS LIKE EXCELL NO LONGER IN BUSINESS.

 I WOULD SUGGEST TO PURCHASE WHAT AVAILBLE IF YOU LIKE YOU RIFLE GET SOME EXTRA PARTS FOR IT.