Ok, let's talk muzzle brakes! Rather, let's read a bunch of stuffy Army papers on the subject. Here we go........
The first is an "Engineering Design Handbook" on Muzzle Devices from the U.S. Army Material Command. Dated May 1968, it is a bit dated. But physics doesn't really change, so the science in here is solid. The document is unclassified and approved for public release, with distribution unlimited.
The second, is a technical report that discusses methods for predicting muzzle brake effectiveness. This one comes from the US Army's Ballistic Research Laboratory, Aberdeen Proving Ground, Maryland.
The group has been reformed and reorganized several times. The US Army Armament Research and Development Command, as noted in the document, is now called CCDC Armaments Center (formerly well-known as ARDEC - United States Army Armament Research, Development and Engineering Center).
I may finish out this 'blog post' at some point, but for now, this Army stuff will have to suffice. For now, check out the Army docs listed above and the compilation work from Cal Zant of Precision Rifle Blog: his latest Best Muzzle Brakes & Suppressors – What The Pros Use.
Also, Jeremy Kahn of Kahntrol Solutions said it well in Greg Connoyer's FB post: "the variables that effect brake performance are; brake design, rifle weight, barrel length, bullet weight, and most importantly, powder charge. Take 10 brakes of different design on a given rifle, with a given cartridge spec, and they will rank one way. However, if you change any variable, the ranking order will change to some extent, and the percentage reduction (from bare muzzle) will change significantly. In addition to measurable differences, there are other differences as well; concussion to shooter, dynamic effect of gases on bullet (effect on accuracy), ease of cleaning (or even need to clean) between designs, and non-linear force on the muzzle (angular thrust). [...] But you aren't going to figure it out without testing, and anybody that says a given brake is best for every shooter or rifle, is lying or ignorant."
This has been my experience, more or less, in designing/manufacturing silencers and brakes for several years now.
Enjoy the 'light' reading...