Dave Kiff holds a copy of John Skowrons’ 6mmBRX reamer print. There are several other shooters 6mmBRX reamer prints available. I know Dave Manson, and DClymer also have prints of the 6mmBRX.

The primary varibles are Throat length, and neck diameter. John Skowron chambers have a .271 neck and he does not neck turn. He is using a .265 or .266 bushing.
A .272 neck also is considered a no neck turn chamber.

I have done a number of 6mmBRX with .268 necks. with .262 – .264 bushings

I know folks who have their reamer ground with only .020″ throat and custom cut their own throats with a throating reamer.

Other use .090, .104, .120 throrat

If you are going to have a reamer made send the reamer maker a resized case with the bullet seated to the depth you desire. Include your measurements with it. That way the reamer maker can check your measurement against his.

there are many dfolks on 6mmBR who have taken the plung and built their own 6mmBRX. All can provide you with good information.

Learning from my own mistakes. Don’t over size the brass just bump the shoulders.

Don’t try to shoot is at extreme velocities. The 3025-3080 fps node will gain you accuracy, ecconomy, and longevity.

Good Luck with your project.

Nat Lambeth