Hello Brian,
I saw this thread already a longer time ago and I thought I have written something, but I was wrong. It's a very interesting and mysterious rifle, now I have to write something.
The stock stock completion code is "2 40 43" and it means 5th October 1943. The first number block "2" is the Day and you have to keep in mind in Germany the week start on Monday, not Sunday. The second number block "40" is the week and the last number block "43" the year. Of course the actual production date of the rifle is after stock completion and the stocks were stock piled, at Sauer & Sohn in 1944 average 16 weeks. Let us suppose it's the case with your rifle, then actual production date would be in January 1944.
The serial number is "2133" without suffix and this lead us to a production date in January. The barrel code "ce ch" fits perfect into the ce 44 range in January 1944. The barrel bands fits to a ce 44 (the stamped ones got already introduced in late 1943).
The transition from "SN on receiver - no SN on barrel" to " SN on barrel - no SN on receiver" happened between late "i" and late "l" block, around June/July 1944. On the barrel is no serial number, just on the receiver and it fits to a early 1944 production.
Now to the mysterious part and you mentioned already the lower case "l" which is a sign of a Astra Werke receiver. In addition the "Mod.98" is in block letters and not the gothic type from the Erma receivers which normally got used in 1944. The Walther receivers in 1943 had the "Mod.98" in block letters, but your receiver doesn't look like a Walther production and in my opinion it's no longer in contention. As determination we come to a "bcd 4" Astra Werke receiver.
But the first "bcd 4" appear in the early "s" block in 1944, the "bcd 4" have the SN always on the barrel and not on the receiver.
Note the reinspection stamp e/37 beside SN on barrel. It reminds me a bit about a "oddball group" of ce 42 and here is a thread about such a rifle:
ce 42 b factory repaired receiver
I noticed something similar with one example in 1943 with a ce 43 and I was thinking about the reasons. Seems like Sauer & Sohn filled in later production, certainly in fall/winter, some rejected serial numbers with rifles with reinspected parts. It would be nice to resume the discussion.
Greetings,
Stephan