While this is the highest known, this depot is nowhere near the scarcest, - some of which I have recorded only a couple examples, it is actually more common than several others, I, IV, V, VII, X are all far more elusive, but XI is in the middle along with IX, XVII and far more elusive that the biggies XX & XXI, there are more XX & XXI known as the rest combined...
My comments in post #5 are reflective of the examples so far recorded, these were clearly made over a period of time as they all have little inconsistencies about them, no two are exactly alike, the roman numeral changes, the FP changes, both in placement and style, and most strange of all, earlier are SRO and the highest are serialed on both receiver and barrel, the reverse of what one would expect.
Of course, like Mike stated, to say much beyond this would be foolhardy as few have matching components, this is probably the most matching we have seen (6316 seems to have matching components, and its finish look strikingly better). Though I still have doubts as to the finish, but as I have long stated, judging finish from internet pictures is always problematic, which is why I rarely do, but this one looks so rc-ish and these are so rare outside of that "condition", I made the assumption (though corrected myself in #9, so Mike's critique must be directed at others...)
Here is a list of known XI rifles (and condition):
XI 296 (bcd/41 - Rumanian de-nazified, some matching components)
XI 657 (bcd/41 - rc)
XI 1241 (Walther - some matching components)
XI 1655 (Walther - probably rc)
XI 1753 (blanko, probably Walther, rc)
XI 1887 (bcd/41 - rc)
XI 6316 (BSW - some matching components, a recent rifle, might be on this forum)
XI 7644 (Walther - some matching components)
There is a huge gap between 2000-6000, as Mike stated, this is not that uncommon though, most have substantial gaps like this, mostly because so few have been recorded. Only XX, XXI are numerous.