New Weekend Knowledge Dump ...

 ... from Active Response Training. Some of the articles/topics that caught my attention:

• Ellifritz included an article from American Rifleman, noting that his articles on .380s have always been among his most popular. The article was positive about the .380 which is a massive change from when I first started carrying a concealed weapon.
• A link to an article from Ammunition to Go on the best defensive handgun ammunition with links to the results of their ballistic gel tests. I knew of Lucky Gunner's tests, but didn't realize (or had forgotten) that Ammunition to Go had done their own tests.
• Speaking of tests, Ellifritz links to an article on using 5/8-inch thick pieces of sheet rock to test bullet penetration and rough equivalents to penetration in other mediums. The author of the article notes that "40 years ago I discovered 4 half inch layers of sheet rock equaled the penetration of 8 inches of thawed deer meat," and "Each 5/8″ layer of sheet rock MAY BE roughly equivalent to 2 inches of calibrated 10% gelatin. This is roughly equivalent to 1.3-1.75 inches of animal."
• A good article on surviving a human stampede. Ellifritz links to the article because of the risk of being caught up in a human stampede as people flee from a shooter; the article mentions stampedes as people attempt to escape from a fire or similar emergency; I would point out that it seems a regular occurrence of people stampeding to get into concert venues. But, frankly, a lot of the principles apply anytime you might find yourself in an enclosure where people are packed together, such as a commuter train in Tokyo during rush hour (speaking from experience). The part about keeping your hands and arms up is important, not just because of the need to keep literal breathing room around your chest, but also so you can grab things to avoid being shoved or pushed off your feet, but also so you can push back against the press of bodies (such as a sudden deceleration of a train).
• An article on the why of the mid-length gas system for an AR carbine, including an explanation of the different length systems and dwell time. IMHO, there is no reason to have a carbine length system for a 16-inch barreled AR when the mid-length system will be less punishing to the firearm.
• A Guns & Ammo article on "deep practice" which will get you better results for your time investment, the author claims. I will have to try it out.
• An article on how to ease into sprinting. This one really spoke to me because, about 10 years ago now, I tore a hamstring when I decided to participate in a foot race at a church activity. 
• And I also found very interesting an Ammo Land article disclosing the original ATF AR15 classification letter and how it refutes the common claim that the AR15 was not meant or intended for civilian use. The letter makes a clear distinction between the semi-auto AR15 and a select fire model that was provided for comparison.