This is my first post so if its not in the right section apologies. I have a specwar762 on order and I would like to install the appropriate brake on my scar17. I've read not to use the factory jamb nut. I assume that I can't just time it and use rockset? Does it need to be torqued to a shoulder, can I use shims with such a small shoulder on the barrel? Thanks in advance for any input.