Thread pitch is 6-48 you can get them from Brownells or try a local gunshop to just buy a few. http://www.brownells.com/rifle-parts...prod10223.aspx
1-800-741-0015 Telephone Orders
Note: Brownells will ship these first class mail in an envelope to save you the cost of more expensive UPS shipping charges..
Stock # 080-533-648AA ($8.73 per Dozen)