It has taken almost a year, but my Marlin CSBL has its threaded barrel, silencerco hybrid suppressor, and vortex venom red dot. I have not been able to find good information about bullet speed and suppression for 38 special out of a 16 inch rifle barrel, so here is what I have found. More hand loads to come.
All rounds are hearing safe. Feet per second is the average of 5 shots. I apologize but I did not write down weather conditions.
Federal 158gr lead ------------------- 950 fps
Magtech 158gr flat nose FMJ --------- 1000 fps
Berry 158gr FMJ w/ 4.0gr WIN 231 ----- 830 fps
WWB 150gr lead ----------------------- 990 fps
WWB 130gr FMJ ----------------------- 1045 fps
I hope that this helps someone. I know that Marlin now has a whole line of suppressor ready lever action rifles. That single hand load of mine shot with a whisper. From now on I will be shooting with the Magtech and working on accuracy for handloads. Enjoy and stay safe.