The original article with tons of detail on the test setup can be found here so I will keep it short. What we do is shoot 5 rounds through a chronograph to get a decent average on the velocity of said rounds without any barriers. After this is obtained we fire 3 times through the drywall with the chronograph on the other side of our wall to get an average post drywall velocity. This will help weed out any funky results and make sure the numbers we do get are valid.
The 12 gauge #6 birdshot has the largest reduction of the 5 rounds we've tested to date with a difference of 17.38%. I tested this because of the internet forum advice I hear all the time about how birdshot is a safe alternative to hitting the bad guy becuase it is not as likely to hurt the innocent people in the next room. Yes it did reduce quite a bit but 1,017 feet per second is nothing to scoff at. Not to mention the fact it is made for small birds not stopping a determined attacker but that is a post for another day. The 5.7x28mm was slowed by 4.72% post wall which is very similar to the original test we did using an AR15 and 55 grain Vmax bullets:
What have we learned so far? Shooting is fun and train until you can hit your target! If you enjoyed this post please consider liking my Facebook page at TheProperGrip. Thanks!!!