The bolt is 4 3/8 inches long, 3/8 inch in diameter, 9/16 hex head bolt, it is threaded for 1 1/8 inches with what appears to be a 24 pitch thread (24 threads to the inch). Also the hole bored in the back section of the stock, nearest the buttplate is 7/8 inch in diameter. Approximately 3/8" to 1/2" of threaded bolt is exposed where it threads into the receiver. The hole bored for the bolt itself is also a 3/8 (+ a hair) since the bolt is a nice smooth snug fit in it. Hope this helps....<><.... :grin: