Its hard to say from this image. Since its new go back to your provisioner and request a new assembly. If that fails. Replace with a new fastener.
Originally Posted by zkovach
I started firing my new m1 carbine at the range and the top wood piece (on the barrel) fell off. On further inspection i saw the bracket that tightens the wood to the barrel was loose. As i tightened this it seemed either stripped or i am missing a nut... which is it? if i need a new "bracket" where can i go to get one. see pic below.