A muzzle brake will not affect the speed of the bullet.
Magna porting is one of the least effective means of recoil control. Look at the Brownells or E. Arthur Brown website to see the many different shapes and designs available for muzzle brakes.
There are really two categories: expansion and baffle brakes. The expansion brakes are like the KDF, BOSS, and Weatherby style. An extension with a bore much larger then the bullet. This brake will have holes around the periphery of varying size and pattern. Work quite well, from 45 to 60% recoil reduction depending on port volume and cartridge.
The baffle brakes are like the fish gill brakes seen on 50cals, JP Ent, etc. Very effective, usually bigger in size and diameter. Effectiveness is a byproduct of number of gills and port/muzzle pressure. Usually better then expansion only muzzle brakes.
In either case, the more gas that can be diverted 90deg. to the bore, the better. The bigger the port volume the better. Lots of small holes or a few big holes really doesn't matter as long as the volume is the same.
Quiet brakes usually have lower recoil reduction then "noiser" brakes- allow more gas to be vented forward.
The most effective brake is the baffle brake that vents backwards - see most 50Cals. Also, the noisiest, highest muzzle blast.
There is a third design concept to brakes that was not mentioned. Inertia/Vortex brakes, we use these to control recoil and torque, they are a quantum leap forward in both recoil reduction and accuracy. [img]images/icons/wink.gif[/img]
I noticed some of you cut your brakes to pretty tight dimensions. Just as a note to keep in mind, any brake with .015" to .022" clearance should be checked on a regular basis. What happens is that the powder from these slower burning large cases peens the edges and rolls them up over time, physically shrinking the diameter of the opening. The bullet jacket will begin to rub and accuracy will suffer greatly. [img]images/icons/wink.gif[/img]
It also depend on the hardness and material the brake is made from.
The Answer brakes I install are made from either 416R SS or 4150. Both are heat treated to 28-30R. For a 30cal brake, the best recoil reduction and accuracy come from an .323" diameter hole through the brake. A maximum of .328".
Never had one that closed up when the heat treat was right. Did see one that the heat treat was bad on and the brake visibly streched though.
I use the Answer brake and it is an outstanding product, particularly when mated with the Answer recoil pad, which has a compression rate matched to the caliber of the rifle (mine is a 7 pound 416 REM). The pad is set to compress 5/8ths of an inch when the bullet enters the brake, so the bore thrust is managed by the pad and then the redirected gasses stop the momentum right there.
The more overbore the round and the slower the powder, the better the brake works. Its just a matter of how much energy the gas has when it expands into the brake.
If the brake is optimally effective, there will be no increase in velocity.
The breaks I use have an internal taper. The taper apposes the angle to which the gas contacts it at.
Consequently, the muzzle breaks I have made are very effective. In my 7mm STW the opening is .320 or so. I found that anything tighter would effect my accuracy.
Roy Bertalotto, who is a member on this board, has done some interesting work with muzzle breaks.
S1 how did you overcome the colapsing of the bore at the end of the muzzle when the break tightened down?
I understand now what you meant by anit-torque break, I thought you were suggesting that the muzzle break (before the bullet exited) counteracted the forces of the bullet in the bore creating torque.