The ports are usually 1/4" or so from the end of the muzzle. Does the muzzle flash of a non-ported gun blind you at night? The 1/4" isn't going to make any difference in the amount of flash. You're going to get a whole lot more flash from the end of the muzzle in a 360 deg flash than any amount you'd get from a couple of small slots 1/4" from the muzzle.

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183rd FBINA