Forgive my ignorance but will the bolt carrier and bolt from an L1A1 operate in an FN upper, if I get a gunsmith to make sure it head-spaces ok? I was under the impression the only difference was the sand cuts. Also, are the gas tube, spring, and piston interchangeable? I have secured a stripped FN upper as a project to hopefully fit on the L1A1 lower (I am aware about the situation with the magazines)
Cheers, Tom
