When you put the forarm on it pushes the barrel back against the frame which makes it seem to be locked up better than it really is. The fitting instructions in the sticky are misleading, a quarter inch engagement of the latch shelf is way too much and will lead to a bad latch up (sorry to whoever wrote this, but you are wrong, an eigth inch is plenty). You may help your self a slight amount by removing the latch release lever and taking a little off the stop it has on it, the stop may be preventing the latch from fully moving up to the end of it's travel. The latch lever stop is a little bump that hits the cutout in the frame just to the right of the hammer. Because of the way the latch engages the shelf very small amounts of change will generate very large amounts of latch engagement change. Be careful when takeing anything off the shelf when fitting the barrel. I learned to first start by using a very flat stone to take off all the tooling marks from the rear of the barrel, this makes the latch up much more positive. Also, I know it is a pain, but remove the ejector parts before fitting the barrel, the tension of the ejector can also fake you out as to how good the barrel really fits. I learned these things after trashing one 17HMR barrel while fitting it to an SB-2 frame to re-chamber it to a .17 remington. It is finished and on it's way back to me now, and I am on my way out to Sea for 3 weeks, so I won't be able to play with it, Big bummer ;^( . Larry