300 BLK with proper bullets is extremely effective CQB. I have nearly 2 dozen 300 BLK from 7-8.5 inches to 16 inches, and two bolt guns. Have done extensive load data and pressure data, and terminal ballistics with several bullets.
We designed a 100 gr CEB Raptor specifically for the 300 BLK some years ago. This bullet was such a success on everything from deer/hogs up to Black Bear, this is the only bullet I load anymore from 300 BLK to 300 Winchester, and will do everything you need or want to do and more for anything you are going to use a .308 caliber bullet for. It is very successful in 308 WIn as well and has accounted for more DRT animals than you can count.
We keep pressures to 55000 PSI for this cartridge. In 16 inches we can run the 100 Raptor to 2550 fps, as we drop down to 10.5-12 inch guns that runs from 2380-2420 fps, dropping to 7-8.5 inch guns you are at 2275-2300 fps. I prefer 10.5 inch guns over the shorter versions for better terminals, although not coming up too "short" with the 7-8 inch guns... Pun intended.......
The only other bullet that meets my criteria for tissue destruction and penetration is the Barnes TAC designed for the 300 BLK as well. At 16 inches and 55000-56000 PSI this runs at 2400 fps, 10.5-12 inches 2250-2280 fps, and 7-8.5 inches 2170-2200 fps.
Why anyone would purposely choose the 300 BLK for Suppressed work I don't know, there are far better choices out there. Now you would have a .308 caliber handgun cartridge? None of the standard .308 caliber bullets are terminally viable at Sub Sonic? None are stable once terminal penetration begins. Choices for bullets that actually are terminally viable at Sub Sonic are specialty bullets that you can get from Lehigh and Cutting Edge, and are expensive, and still only .308 caliber. In my opinion, 9mm Sub Sonic is far superior to .308 caliber Sub Sonic when it comes to Terminal Performance. With the exception of the bullets designed for Sub Sonic work. I have worked with JD Jones on these projects with special bullets in years past and they are viable. However, I doubt seriously that many of you are serious enough about Sub Sonic to go the distance and work with Sub Sonic designs???? Instead, working with simple standard .308 caliber bullets. If so, then 9mm is far superior in that department simply because of caliber and stability, once terminal penetration begins. At sub sonic .308 caliber bullets do not expand, they are not terminally stable, they tumble upon entry, penetration is poor, and terminal paths are unpredictable. And no, tumbling is not "Terminally Viable" or nearly as destructive as decisive and true penetration, and expansion or non conventional tissue destruction. One reason JD and I were working with better bullets in .308 caliber at Sub Sonic was for various State Dept that were charged with "Deer Control" in urban areas. Standard .308 caliber bullets were causing more issues than the solved at Sub Sonic levels. JD and I worked with bullets that would fragment at Sub Sonic velocities in the nose section, and then allowing a solid full caliber base to penetrate deeper, and straight. Causing far more trauma to be inflicted, and therefore better terminal results. This initial work was very successful and therefore carried over to the bullets you can get today from Lehigh and Cutting Edge, and probably some other places as well. In these cases, then Sub Sonic is a viable option for 300BLK.......
For my use, I much rather have that 100 Raptor loaded for any serious work, or for hunting. It is well proven. I keep a 10.5 inch gun close at hand. Although, I do admit, I don't feel under gunned with a 8.5 inch gun on the boat.
The 300 BLK is a superb hunting firearm for kids and women as well. Loaded with Raptors, the cartridge is extremely effective as well. It's not loud and no recoil at all. A friend of mine in NC has some young boys, age 8-10, and not all that long ago his 8 yr old shot a nice bear with his 300 BLK and the 100 Raptor load. Bullet went thru heart broadside, exited, bear took 1 step forward and DOWN for the count on the spot. In addition they have taken several deer and I hear even a few alligators as well...... Perfect for Kids and the Ladies as well as grown men...........
Currently I am having SSK build a 7.62X40 for my daughter and her future deer hunting. 7.62X40 is a longer 300 BLK, and about 200 fps faster across the board, still no recoil or noise and works perfect in a Winchester M70 that was chambered in 223............ Oh, and it will be loaded with 100 Raptors at 2800 fps.................