I got this what I believe is a 9mm semi auto rifle bolt in a box of gun parts at an estate sale. Had a lot of HK stuff and some Uzi stuff, but it isn't an Uzi bolt, looks similar to a Thompson but it isn't. I know it isn't complete since I did find one image of the same bolt on Google image search, but the link went to pic click for a Remington 770. Any help would be appreciated.