Just finished up the testing of the #4 buckshot round from Remington (#12B4) Here are the conditions and results.
-20'' Remington 870 barrel (no aftermarket chokes, as it comes from the factory)
-300 feet above sea level
-Test rounds fired from 10 feet
-FBI spec Clear Ballistics gel block (more on this below)
-4 layers of denim
-1234 fps average velocity
-11.5-15'' of penetration
The manufacture of the gel block, Clear Ballistics, claims their gel meets FBI specs for testing. I calibrate my gel per their specs prior to testing and use 4 layers of denim per IWBA protocol.
However, by no means am I saying this test is a substitute for the great work industry professionals like Dr. Roberts and others do. I'm just a shooter that likes to learn about the products I use.
Here's the video showing the test, the permanent cavity, and a discussion of the results:
#4 Remington Buckshot HD Video Test