20" if I was cutting.
Which I probably wouldn't, I'd buy a carbine.
Or a beat up good old rifle to cut down, but never want to hack it!
Anyway, under 20 is short and gets louder, fast.
If you leave it any longer than 21, it's not really worth doing.
I prefer rifles around 20".
Not that a longer barrel can't be put through the same places,
But it requires more effort, and if your 24"+ plus barrel hits something,
I'll bet you a quarter it's going to be out past the 20" point.
