How much clearance is there between bullet size and muzzle brake hole size?

For instance, what is the size of the muzzle brake hole on a .30 caliber rifle?

I'm thinking they go for 30 thousands clearance. So 50.060.

Usually about .030" or a little more clearance on each side. So a .308" bullet would have about a .368" hole or bigger.

http://bulletin.accurateshooter.com/2016...-effectiveness/

Great article...the answer is .020

Ahh. Yes, great article. Twenty thousanths is much tighter than I would've thought.
Grassy Azz.

If anyone else has any input I'd be glad to hear it as well.

I may be thinking suppressor. Would they be different?

Probably more clearance in a suppressor since it's longer and the last hole may be out there 6-8" instead of 3/4" or less from end of barrel.

I'm getting amazingly good flash suppression with NV on my 6.8 using an oversized A1 hider that's threaded 5/8-24 and made by Tromix for the 458 Socom.

I know a suppressor is about .030", and that was the data I figured as well for a muzzle brake.

If a 0.30 caliber has a brake with a 3/8" (0.375") hole, would it substantially degrade the effectiveness - or would it not be enough to matter that much?

Prob not enough to matter. Call a few muzzle brake companies, and see what they say.

I was just thinking of nominal SAE drill bit size. There would prolly be a metric size drill bit that gets closer to the desired diameter.

I will. I know of a couple of people in my area. I would buy the muzzle brake of course, ...but I wouldn't be above making a basic one.

I have made quite a few. Use a drill bit to get close but then use a small boring bar to finish up. This not only will get you any size desired but the hole will be true unlike a hole made by a drill bit.

I'd be shocked if you could feel the difference. I shoot a .30 brake on my 6.5, and it's very effective.