if the sideports are shaped correctly you don't need top holes .
here is a 4 port beast. 338 lapua
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here is a early design muzzle brake and more , with top holes on my 300 wby. you can see the difference in the side hole shape .
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I shoot with a guy that has a terminator, the chassis gun in the pic . that brake blows back hard enough that it disturbs my labradar to the point it will not give a reading . I position the labradar over the front bell of the scope . so far that is the only brake that bothers the labradar in this position .
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one guy uses a bastard brake with 2 rows of top holes . this is the heaviest rifle out of our group , it's probably 25+ pounds . I don't have an opinion on it , one way or the other . it seems to do what it needs to do , and it can be shot through my labradar set up over the scope . another guy came with a savage with the factory brake . it only took a handful of shots and he had enough recoil, for the day . a week or two later he had a 5 port beast , he can shoot it now .
radial brakes blow to much dirt to be used on a prone rifle . this is a 7 rem mag
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this big radial brake doesn't reduce recoil as well as the 4 port beast .
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