Ran into one more problem, and it may just be my ignorance. On the threaded piece of the extention tube there is a extended piece that has a slot that could possibly be for a sling. The problem is when you slide the forearm on, the barrel has to go on next and you can't thread the extention piece on because the extended piece hits the barrel as you start to thread it. I am soooooo confused, it just can't be this complicated.