Recently (last few years) it has been popular to call the AR-15 a “high power” rifle. Which is funny, given how relatively *low* power it is compared to a lot of battle and hunting rifles. The 5.56 mm round used in the AR-15 develops in the range of 1,700 to 1,800 joules muzzle energy; the 7.62-51 mm round in the obsolete M-14 rifle gives you 3,300 to 3,500 joules. The 30-30 Winchester, introduced more than 120 years ago and used in hunting rifles, gives you around 2,500 joules (I had a 30-30 once upon a time, and when you pulled the trigger on it… you knew it). The .50 Beowulf round used in modified AR-15s develops 3,200 to 3,900 joules. Heck, the .50 Action Express round used in *pistols* develops 2,000 to 2,200 joules.
But then there are the weapons described in this video that develop up to 57,000 joules (the 14.9mm SOP round is still supersonic FIVE KILOMETERS downrange). Yimminy.
(note: irritating commercial for a video game is built into the beginning of the video. Shrug. Errybody gots to get paid, I suppose.)