K11 matching serial number question

[Uncle Ray]

Hello,
I've just acquired a nice K11 and notice every numbered part matches up EXCEPT the the rear sight which has a 3 digit number on ramp and slide matching to itself.

I've only closely examined one other K11 and it had the same number situation.
Is this the norm for K11's ?

I also have a K31 and think I may be getting addicted to Swiss Rifles. What books should I get?

Thanks for any help you can give.

Regards,
Bob Gold

G'day Bob,
Interesting question. My K11 was re-barrelled in 1915, having been an earlier pattern converted to K11 configuration. My new replacement barrel is by Hammerli, and like yours, the sight ladder and slide, although having been stamped with a three digit number, does not match the carbine number which is six digits.
Despite it not matching, I'm sure that in my situation the odd-numbered sight came with the Hammerli barrel, rather than being replaced later. This is only my opinion, of course, despite the Hammerli barrel being stamped with the rifle number, albeit not exactly using the original period stamps. For what it's worth, my sight number is 542.
At first glance they look the same, but there are minute differences in the serifs.
Take the carbine out of the stock and check for additional barrel numbers underneath.
Good luck
Uncle Ray