Jeff Findley wrote on Thu, 23 May 2019
07:13:11 -0400:

In article ,
says...
Same thing will happen for SRB segments too. It's not yet clear what
will happen when those run out.

I was always under impression that only the engines were leftover
inventory from shuttle and limited in supply, and that the core stage
and SRBs were built new, based on designs for shuttle.


I believe you're correct here. I think the original intent was to use
SRB segments that were identical to those used with the Shuttle, but I
think that intent changed.



Unless something has changed, they've been using shuttle SRB components
from the very beginning for the 5 segment SRBs:

https://www.space.com/28775-worlds-l...nasa-test.html

From above:

The individual segments though, use the same case parts that
were recovered and reused during the space shuttle program.
As such, the first SLS qualification motor (QM-1) being
tested on Wednesday is comprised of hardware with a historic
past.

Do you have a cite for the assertion that new casings have been made?


Turns out that a lot of Shuttle legacy parts are used in the SLS SRBs.
They're different, though. The big difference is that SLS SRBs have
an extra segment over the Shuttle SRBs (5 vice 4). So they will
eventually run out of those legacy parts (but not until well after
they run out of RS-25 engines).


--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney