HW44 with a HW100 carbine air cylinder. It works!!!!!!!
I'll enable some, too.... There is a HW44 for sale right now!! 😄 Right here: https://www.airgunnation.com/threads/wts-weihrauch-hw44-pistol-with-w-scope.1288732/#post-1489185

After looking at Jarmstrong's conversion, I decided to do the same thing to my HW44. I had already outfitted it with the Rink Formgriffe stock (Shoulder-stocks) but decided to go all the way with the carbine conversion by replacing the pistol barrel with a HW110 .177 310mm carbine barrel. I decided to keep the pistol air cylinder because it was adequate for my needs. I get two magazines out of one fill and that met "good enough". I ordered a barrel from airgun spares in UK and it arrived in four days with no import tariff issues. I disassembled my current set up, removed the barrel (it just unscrewed), screwed the new barrel in, put it all back together and that was it. I got some additional guidance from J on some plastic holders for my vice to secure the barrel when I removed the old one. A little extra mussel power was needed because the barrel had locktite applied at the factory.
Original setup.
Finished Product