As I said...do a search on the net and you will find many providers...my local 'smith does brakes for $125-150 depending on which brake you pick and how much blending or bluing needed. It is a simple thread job and you need to keep the brake exit hole as close to 0.020" over bore size to get the maximum recoil reduction benefits.
MUZZLE BRAKES_ROSS SCHULER...rem40xb1@msn.com is the guy who does the NEF jobs.
I made a bunch of different type brakes to test a while back...they all worked to a greater or lessor extent depending on the size and way the holes were arranged. The loudest was one with just a 3/4" hole drill through side to side and two 3/8" holes on top. The quietest was the type with the many small holes either arranged in a slight spiral or in a straight line, the "Quiet" Gentry type. I copied, modified and changed many parameters, used steel, SS and Alum with equal success while I was playing around...didn't seem to matter, although the SS looked better on CM or SS I think.
I can buy a very nice brake from Harrall's Precision for 30-35 bucks so making one...if you've done any amount of lathe or mill work...is just plain dumb unless you want to learn or like wasting time...I would rather getrdone then go shoot. It takes me about a hour to setup, thread the barrel, install the brake and setup the taper cut and ream the exit hole then blue...and that includes coffee "brakes" If I was making the brake from a piece of roundstock I can figure on 1 to 8 hours depending on the design, number of holes, amount of setup and tool swapping then inside threading. Even as worthless as my time is...30 bucks and a screw on job seems much more reasonable.
In todays world of CNC machinery the same brake can be produced in minutes...and if you don't have to mess around dialing in the 3-4 jaws it is really easy...not counting the knowledge need to set up the program. I would give two Yankee dollars to have CNC machines in my shop rather than the manuals I have.
You will have to get used to the air puff in the face. It startled me the first time it happened but it doesn't bother me now. That's just your local variety physics teaching you lessons.
Anyway...we all have our different tastes as far as liking or not.
'Njoy