Might be worth sending Dave Butler an email from DB-Schietsport.
He's helped me out in the past and ordered something specific for me from Weihrauch.
Usually if it's in the Weihrauch catalogue he can get it for you
They don't list .25 on the website but might be worth an ask
DB-Schietsport
Dave Butler
Tolpost 8
5701 HE Helmond
0492-538372
info@db-schietsport.nl
https://www.db-schietsport.nl/en/