I wasn't asking bout the rim size on the 6mm Lee Navy case, as I have a Lee Navy rifle I've handloaded for ans shot, and a box of factory loads from the 1930's. It does have a .448" rim.
The prototype Lee Navy case did have a rim, but never made it into military service. By the way, it used a .238" diameter bullet, even though it was called the .236. The final version used the RIMLESS case with the dimensions you listed, with a .244" bullet. (Apparently neither cartridge used a .236 bullet, despite the name of the prototype rimmed round and the mistaken claims of various references, including Wikepedia.)
But I wasn't asking about all that, since I know the details very well thanks to working with my original Lee Navy rifle. I was asking about why the reference you cited calls the case "semi-rimmed," because it isn't, any more than the 30-06.
Winchester put a .473" (".30-06 sized") rim on the 6mm Lee Navy case to come up with the .220 Swift, so they could use the .270/.30-06 bolt face and extractor size in the Model 54 rifle. That resulted in what is generally called a semi-rimmed case, with a rim significantly larger than the case body but including an extractor groove. But the original 6mm Lee Navy case doesn't qualify as semi-rimmed.
