I was getting ready to go out this coming week to load test some 180 Hornady's with Staball HD ,was cleaning the barrel and decided to take the break off and see what the inside dia. is. To my surprise it was as near as I could tell about .330,seems quit large for a .284 dia. barrel , according to wat I have read it should be about .304, Pete
Muzzle break inside dia. ?
- Thread starter Hard Head
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Sounds like a 30 cal brake.
That is what I thought, Bergara does not make a break for a .284 dia. barrel so they must put a .30 cal on I wander what the max dia. for the 6.5 is. Pete
Yeah definitely sounds like a brake designed for .308, but it should work well. I can't recall where it was, maybe YouTube, but I have seen some testing and a slightly oversized brake shouldn't hurt the efficiency too much.
Correct- this absolves them of a potential liability issue of having brakes that look the same with different sized holes in the end. (25 caliber brake with a .308 bullet = something bad.)
redneckbmxer24
Well-Known Member
That's less than .050 over, most brakes are .030-.040 over so it's not that much larger. I wouldn't worry about it.
sable tireur
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As with most technical requirements in firearms manufacturing, there are opinions galore.
Brake diameters is one of those topics which gets questioned or discussed frequently. Some argue, some discuss. There have been numerous test situations conducted but no scientific based pressure/velocity tests. Many brake manufacturers simply drill/bore a .22 caliber hole and let you resolve the debate on your own or with a gunsmith.
There is one theory put forward that states that a hole too small or close to the bullet diameter actually reduces accuracy while slightly larger holes appear to not affect accuracy at all or as much as one smaller. Who knows?
Generally speaking and please, in my opinion only, adding 0.020" a side or 0.040" overall seems to be an appropriate diameter. Be aware that the barrel bore and brake bore MUST be aligned perfectly!
However, whatever you select or produce, measure accurately and check with a single bullet BEFORE loading and shooting. I wish I had the pictures I took several years ago when someone actually shot a .30 caliber bullet through a .264" diameter brake. Woke his butt up!
Be careful, measure and check!
Brake diameters is one of those topics which gets questioned or discussed frequently. Some argue, some discuss. There have been numerous test situations conducted but no scientific based pressure/velocity tests. Many brake manufacturers simply drill/bore a .22 caliber hole and let you resolve the debate on your own or with a gunsmith.
There is one theory put forward that states that a hole too small or close to the bullet diameter actually reduces accuracy while slightly larger holes appear to not affect accuracy at all or as much as one smaller. Who knows?
Generally speaking and please, in my opinion only, adding 0.020" a side or 0.040" overall seems to be an appropriate diameter. Be aware that the barrel bore and brake bore MUST be aligned perfectly!
However, whatever you select or produce, measure accurately and check with a single bullet BEFORE loading and shooting. I wish I had the pictures I took several years ago when someone actually shot a .30 caliber bullet through a .264" diameter brake. Woke his butt up!
Be careful, measure and check!
crashlanding
Well-Known Member
When I was researching brakes a year or so ago, many manufacturers don't offer a 7mm, if memory serves me right, they went .22, 6.5, .30 and so on. If your cartridge was 7mm, you bought the .30, I can tell you that on a 7prc a .30 works well compared to not being braked
Varmint Hunter
Well-Known Member
About .030" over is standard, I believe. However, when I ordered a SRS brake for my 7PRC, the brake that I received read .284"-308". Apparently, they do not make a .284 brake. Studies have shown that using a brake one size larger has very little effect on the brake's efficiency.
Doesn't matter according to the owner of Terminator Muzzle Brakes as long as it is, in his words
