I've been doing some 'kitchen table' assembly on my real parts Obi-Wan ANH saber, and testing a theory;
Personally I believe that the original Tunisia saber was assembled with parts of Browning booster bearings inside, as well as a simple piece of pipe for the clamp spacer and the grenade striker-end cap still in place to keep everything aligned and intact, and this is the theory I'm testing here.
I know that it will never be proved but I'm convinced the brass-work, bearings and pipe were all in there, just because it's the easiest way to do it and it keeps everything lined up properly.