I have a Holland muzzle brake for sale. It is 3/4x28 it has been installed on rifle and bored for .284 but never fired. Would be great for 7mm or larger build. Please note the barrel diameter needs to be between .775 to .850 at muzzle for seamless fit. These are great breaks I had one on my .338 Lapua and loved it. Holland's Quick Discharge Muzzle Brake 3/4"-28 Thread Stainless Steel - MidwayUSA Will let it go for 50.00 shipped.