Adventures With Muzzle Brakes

A couple of years ago I got involved with brake development and experimentation. This was purely for my own edification. I'm just a hobbiest and needed something to do!

I bought a brand new Savage 112 in 308 with laminated stock and SS fluted barrel to be used as a test bed. I threaded the barrel to 1/2-28. This is the thread that most brakes are available in since it is the standard AR-15 thread. I would be testing aftermarket available brakes along with my own designs. I made a rifle rest that would allow the rifle to recoil and the amount of recoil to be measured. I tried to set up a scale to measure this recoil force, but it was inconclusive. I made over a dozen brakes for this rifle. All different size port holes from many, many small holes to just two huge holes on either side (sort of like a military tank compensator). I would start out with the exit hole a very few thousands over bullet diameter and ream it out in .005" steps, testing between each enlargement. I tried different lengths. How long is too long? Different materials. Different hole spacing and location. Here is what I found....

Exit Hole- If the exit hole is too small, ie <.005" over bullet diameter, accuracy suffers. Accuracy really suffers if the exit hole is more than .25" deep. The depth of the exit hole creates a "tube" the bullet must pass through on its way to the target. If the depth of the exit hole is too shallow the metal around the hole will erode very quickly. There is not much heat and pressure (5000psi) at the muzzle, but over time a thin piece of any metal will fail.If the hole is too small, I believe it is the air trying to get by the bullet that upsets flight. Best accuracy and effectiveness of the brake was obtained with .020" over bullet diameter. There was no measurable reduction in recoil between .005 and .020. Measurable change in recoil happened at .040" over bullet diameter. Any exit hole over .040 and the brake began to lose effectiveness rapidly.

Holes- Most effective braking was with a brake 1" in diameter with a 3/4" exit hole on each side, just infront of the muzzle. The bullet passes through a cone of 35 degrees before it exits the brake. (Like the tank example), Incredible reduction of recoil. But loud and ugly. Very easy to make since you don't need a spin fixture or a dividing head. As far as individual holes, it make no difference the diameter or amount as long as they are large enough and plenty enough to bleed off all the gas trapped in the brake. I've built brakes with 48 - 1/8" holes and 30 - 3/16" holes and they both work identical. I've drilled the holes completely random around the brake (looks like hell!) and in straight patterns and helix patterns....no difference on accuracy or reduction. I now use a left to right helix of 3/16" holes .010" apart at a 2 degree off set. A total of 5 holes in a row, six rows for a total of 30 holes. The brake ends up at 2 3/4" with a 1/2" thread depth for an overall extension of the barrel of 2 1/4". The helix keeps the brake tight and it doesn't need to be indexed. If the brake is indexed so the holes line up with the barrel, after removing it a few times the holes will shift a few degrees and look less than professional.

Material- I've made them of Stainless, CM, and Aluminum...No difference at all. The Aluminum brakes harden somehow after repeated firring and I have one on an AR-15 with over 12,500 rounds (Moly test gun) and the brake is perfect.

Holes on top only- In my tests, not having holes all around the brake effects accuracy a bit. I believe it does something to the bullet by the air pushed ahead of the bullet creating unequal turbulence in the bullet path. I've tried a few brakes where I drilled only holes on the top, test fired, and then completed holes on the bottom and in every case, accuracy improved. Put an old blanket down if you don;t want to kick up dust in the prone position.

Expansion Chamber- A brake bored out to thread diameter right up to the exit hole is much more effective than a brake where the bore is exit hole for the full length, Having the bullet traverse this large expansion area somehow improves accuracy and there is a marked reduction of recoil.

Effectiveness- The higher the pressure of the particular round, the more effective the brake. I have over 20 rifles with brakes. The 220 Swift is the king of reduction. Followed very closely by the 25-06, 6mmRemington, any Weatherby small bore. With a proper brake and a hot handload under a 40 gr bullet, the Swift will move 1/2" to the rear and 0 muzzle rise! Big boomers with low pressure like 45-70s and shot guns benefit the least. I have two identical Remington 700s both with identical brakes. One in 308 and the other in 300 Win Mag. Both shooting 155 Sierra Palma bullets, the Win Mag about 300FPS faster, and the Win Mag has measurably less recoil! Must be the pressure / amount of gas available.

Length- After 3" there isn't enough gas left to do anything. The longer the brake, the harder it is to hold concentricity of bore exit hole. If the exit hole isn't +-.0005" , accuracy will suffer.

Factory Brakes Available- I haven't tried them all but of the ones I've tried I will only recommend two. The Vias brake is excellent! Very difficult to make in the home shop. Besides a series of holes around the brake George Vias bores a series of holes to intercept the radial holes, thereby bleeding some gas and noise out of the front of the brake. You lose some braking effectiveness with this method, not much, but you gain a measurable reduction in muzzle blast and noise, Darrel Holland's Ultra brake is IMO the most effective brake on the market. It does everything right! Expansion chamber, exit hole, number of holes, length. It is a quality product and it is inexpensive ($60 in CM. $75 in SS - Midway) And Darrel does about the best installations I've seen. (and I've seen some horrible, nearly unsafe, installations) The JP Enterprises recoil Eliminator (you may have seen it, it looks like a tank brake) is the most effective reducer of recoil. Period! But man, on anything but a 50BMG it is one ugly device. And LOUD! Just too much muzzle blast for any hunting rifle. Hope this helps those of you interested in building your own brakes.

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