Once you get to a certain shroud length you start reaching a point of declining returns, so with a really long shroud and just a 12″ barrel you might only take a tiny amount of noise away from the gun compared to simply baffling the frame without a shroud.
Plus the hammer is noisy anyway.
If I was going to put a shroud that extended say 8″ past the end of my gun then I’d just put a 24″ barrel in there as opposed to a 12″.
You only need a little bit of extra space ahead of the end of the barrel for it to work well enough, even though the barrel is double the length, you still have a TON of space behind the barrel back into the frame with a 24″.
Seems a shame to be to have a 44″ long gun with only a 12″ barrel…
if you already have the barrels like it seems you do. I’d try the longest I had and see how loud and if thats too loud go down a size and if that works fine, great, but if thats still too loud then I’d improve my baffles and then try the 24″ again.