muzzle break size

[cannonboy]

When a muzzle break is made is it machined to the same size as the barral, or .001 or .002 over?

 

[SuperCub]

Depending on the make and style, they come both ways.


All are very loud and obnoxious.


.

 

[cannonboy]

I'm a machinist making one for a 300 win mag thats going to be in a movie. They want it to took something like a Barret BMG, but I just can't find info on the size of the barrel.

 

[Pepperpopper]

What I normally do is just get a good profile of a likely candidate, and import it into my cad program. Just go to some website and right click a picture then put it in a file on your computer. In the program I use one can't resize the jpegs, but I will quickly draw over the outline, and then resize the "drawing" to a known dimension like the oal. That process is simple since the screen shows the oal in inches, which could be anything based on the picture. All I need to do is change that dimension. If a person doesn't know how to draw in cad, even at this simple level, all you need to do is use the measurement fascility. let's say the picture is 4.2 inches in OAL, then the barrel will be some part of that like .1 in diameter. .1/4.2 x say 50" (OAL) will scale the part you want. This method is very accurate. Not helpful for the thous. of inside dimension, but certainly great for overall dimensions.

 

[John Marshall]

I would go a little more than that. You shouldnt assume the threads at the end of the barrel to be perfectly concentric with the bore of the rifle. There often not. I would allow at least .002 for clearance and .002 for machining error in the threads. If it is for a movie and accuracy means nothing than I would stay on the big side because it wont hurt anything.