I am not a suppressor guru. I bought a 6.25in, 12oz suppressor from Idaho Suppressor Works. It’s their Barrel Forward titanium model. So it’s 6.25in, but threads over the barrel making it add less than 6.25in to your overall length. Small company, close to my home and they gave me 25% off which basically covered the paperwork and stamp.
It’s on an ultralight 6.5 with 18in barrel. Shoots like a pellet gun. I have been waiting over 6mos for my second suppressor. Exact same model. Plan is to put it on a 300WM. So I can’t answer your original question yet… Plan as of now is to put it on a 19in barrel and I’m assuming/hoping it will function similarly as my first.