Barrel whip will cause this too, but usually on longer thinner "sporter" barrels like on new BARs and those remington auto with the skinny barrels. If your is a heavier shorter barreled baby like is common on AR platforms, you have a miss alignment problem in the machining as I described before.
There is another type of muzzle brake. These are "installed" by porting (drilling or cutting angled holes or slots into) the barrel itself. Such brakes avoid the added length and the slight bulge at the end of the barrel of a screw-on muzzle brake. They are a neater installation and cannot loosen with use. On the other hand, they slightly reduce bullet velocity, tend to collect fouling, make the barrel more difficult to clean, and, most importantly, cannot be removed.
"You have enemies? Good. That means youve stood up for something, sometime in your life." - Winston Churchill
Suggested gun control movement talking point: "We're OK with guns to keep our families safe, we just don't want you to have them." - Joe
My buddies long distance target .308 is dead nuts with his custom hand loads . He put a brake on it and it would shoot about 15" high with the same ammo even in a shooting jig he uses to sight stuff in with .. Take the brake back off and its right on . I though that was pretty crazy that it was off that far .
Dude, come'on, that's some crazy MOA right there! Really!?
It's not just the speed of the bullet. Barrel whips a tad when you shoot. Bullet HAD been leaving barrel on an UP swing. Different weight on the muzzle, different vibration pattern- bullet now leaving on a DOWN swing. You can't see it- too fast for the unaided eye- but the vibration is there. Trust me.
Yeah buddy, I also have mini 14s, know about that barrel movement. But the barrel on this beast is short and heavy, not saying it isn't happening just surprised.
OK, there are two posts I'll try to answer here. First I doubt the brake is shaving lead since I shot the best group so far after I put it on. Second I raised the scope 20 clicks, it went right back where it was and stayed there, I think as the round count climbed I would have gotten used to it and shifted back.
Mini's have those skinny barrels, also ruger doesn't stress relieve them very well so they twist and turn like mad as they change temp.
One way to determine if your brake is concentric with the bore is to move it 1\4 of a turn. See where your zero goes. If the zero stays the same don't worry about it.
Also if you aren't using a bench rest its hard to tell if your equipment isbetter or if you are. Shooting from a rest is the way to test equipment cause it helps eliminate human variables.
Anyway if it shoots better for you that's great, since that's the point anyway.
I don't exactly use a bench rest. I have a framed up stand with a bulls bag and some sand bags the top is notched out so you can lean into it, it's very sturdy but you shoot standing. This happened because when we first started working with sabot shotguns my friends and I went thru several barrels and scopes and lots of slugs. Standing was easier on us.
Since it's Easter I'm going to give the neighbors a rest on the gunfire and with my schedule It will be next Sunday before I see daylight here again. SWFA is shipping a new scope so maybe by then it will be mounted and I'll be shooting again.