plz DELETE

[trevj]

Thanks for the pic. I’m still confused how that will fit down a 7mm hole, 2” in depth to meet the face of the barrel to true up the bore of the muzzle brake.
I’m missing something here.

Maybe it would save some time if you gave a little of your background.

Essentially, any single point tool that you can fit down a hole to turn it true to the axis of the spindle, is a boring bar, whether it is boring out parts for ocean liner engines, or parts smaller than most watch makers would ever see.

FWIW, I had and built a holder for, a boring bar that would easily fit down a 3/16 inch hole, with index-able carbide inserts. But I much prefer HSS bits for such work.

 

[Al Flipo]

So that kind of sounds like an end mill with one flute then? Not a bore bar. And you run it in till you contact the face of the barrel?
I’ve never seen a brake of appropriate caliber have projectile contact, that to me is a catastrophic mistake.

A boring bar is any single point tool that can be fabricated to enlarge a bore, you also need to understand that the expansion chamber in the brake, just in front of the muzzle, limits the length of the area to be machined. If you have any machining experience at all, you must realize that enlarging a small hole/bore, with a boring bar, is not a complicated procedure.

 

[cooperod]

Brake design

I think I now understand where we differ. Brakes machined here never have engineered expansion chambers.
The bore is .020 over the full length, often on a hunting rifle that bore length is 2”. I have found no benefit to expansion chambers. Yes, boring a hole is not a complicated process. Began machining in the late 80’s, gunsmithing in mid 90’s, but I am not a professional machinist anymore. CNC took the fun out of it for me.
A 12” x .250 boring bar is not a tool I’ve had any practical application for, that’s what reamers do.
To the OP, apologies for the derail.

 

[guntech]

A 12” x .250 boring bar is not a tool I’ve had any practical application for, that’s what reamers do.
To the OP, apologies for the derail.

It isn't a 12 inch x .250 boring bar... it is 2 inches long and 3/16". I don't think you really understand how that tool is used...

If you are simply opening a brake up reamers will work fine, even a drill can do that... but that's a different process than boring an installed brake.

 

[cooperod]

Seeing as you said it was 12”, I took that as fact, my apologies.
No confusion over the difference between boring something and reaming a brake already in place.
I completely understand what your saying your doing, but disagree with it’s need and gains value.
Have work to do, so I’m out.

Home made boring bar, 12 inches in length, takes 3/16" square 'bits', fit 1 inch holder or 5/8 inch holder.

 

[pjs]

I use a solid carbide boring bar that does a minimum bore of .250". They make them even smaller than that but it is not needed for muzzle brakes. They work well because being solid carbide they are very rigid and don't spring. Great for the bolt counterbores etc too.