Profiling/contouring a barrel blank

[70oldsracer]

I want to profile a barrel blank between centers on my lathe. How important is it to use a piloted 60 degree center tool on the muzzle end before I put it onto the live center?

Thanks,

Frank

 

[J E Custom]

I like to single point the muzzle square (90o) And then use the live center against the rifling to make sure that the live center is centered in the bore. (Chamfering tools can drift off center) and the chamfer has/should be removed when re crowning anyway to give the crown a clean crisp edge for best chance of accuracy.

After re contouring between true centers, then you can single point re- crown to clean up any chance of bore damage from the live center. This method will give you a true centered contour.

I never trust the factory bevel to be true and don't like them anyway
for part of a crown. (They are there for ease of cleaning).

Just the way I like to re-contour a barrel.

J E CUSTOM

 

[70oldsracer]

So I don't need to Center drill the muzzle first to get a true 60 chamfer for the live center to ride in? Just make a truing cut on the muzzle end before I use the live center for profiling?

 

[J E Custom]

So I don't need to Center drill the muzzle first to get a true 60 chamfer for the live center to ride in? Just make a truing cut on the muzzle end before I use the live center for profiling?

That is the way I do it and it works very well.

Just stick the live center in the trued bore and lock it down. Don't over spin the barrel while contouring(I will normally take very light cuts of .010 to .015 and run about 250 rpm spindle speed to prevent tool push.

With a good sharp insert or tool bit, this will give a finished cut and require little if any sanding that could change the surface dimensions.

If it is a good job, there will be absolutely no run out that can be measured.

You may be shocked when you see the amount of run out with the existing contour.

J E CUSTOM

 

[shortgrass]

What type of follow rest do you have?

 

[70oldsracer]

What type of follow rest do you have?

The follow rest is the one that came with the lathe. I only have a 9x20 import lathe. It's the one with 2 brass fingers.