Re Crowning

[270]

Does anyone have any opinion on hand turned piloted crowning tools, ie
http://www.brownells.com/aspx/ns/store/ ... =080591243" onclick="window.open(this.href);return false;

It is hard to get a simple job done here without waiting weeks or months

[270]

Actually I mucked up the link, would use the handle and an 11 degree cutter.
How far would you take it back?
Is this a reasonable prospect?

[Kenny]

270

I will start the arguments coming for ya......everyone has their own way of cutting 'the best' crown

I think you only need to remove the damaged part of the lands........maybe 20 thou and have a look and take more if you need to. The main deal is you need to ensure the cut is square across the bore, thats hard to guarantee without being able to dial it in with a range rod and dial gauge......just my thoughts

KY

[Tony Z]

270 as i said on another post, the crown is the most critical part of a barrel.

When a shot is fired, the hot gas evacuates from the barrel, leaving a vacuum. This negative pressure allows cool air to rush in thus cooling the high exposed corners of the lands. After time this cooling effect work hardens the SS steel doing a couple of different things like pieces of the barrel on the exposed lands corners can break away and the heat cold heat cold repetition has a stress relieving effect where the muzzle can bell out. Most muzzle belling is not just from a cleaning rod. Cleaning rod wear is very clearly seen under high magnification as a furrow at 6 o'clock most commonly. Generally this muzzle damage is known as just simple muzzle erosion and is not to dissimilar to throat erosion in appearance.
From my experiences, 5 mm is the minimum barrel length i would remove after 400 shots on a magnum. The same 5 mm on a mid size cartridge after 600 rounds and with a small cartridge, 800 rounds is the line i cut at but maybe just 3 mm this time. The 6 BR as i said earlier is very abrasive on barrel crowns and i do re-cut after 400 rounds and remove about 5 mm.

Jethro Bodine.

[daisy]

Here's a link that might help.

I have used a brass screw with rubbing compound on my Ruger stainless to clean it
up. The biggest problem was finding a big enough round head screw.

http://video.google.com/videoplay?docid ... 0072573269" onclick="window.open(this.href);return false;

[270]

270 as i said on another post, the crown is the most critical part of a barrel.

When a shot is fired, the hot gas evacuates from the barrel, leaving a vacuum. This negative pressure allows cool air to rush in thus cooling the high exposed corners of the lands. After time this cooling effect work hardens the SS steel doing a couple of different things like pieces of the barrel on the exposed lands corners can break away and the heat cold heat cold repetition has a stress relieving effect where the muzzle can bell out. Most muzzle belling is not just from a cleaning rod. Cleaning rod wear is very clearly seen under high magnification as a furrow at 6 o'clock most commonly. Generally this muzzle damage is known as just simple muzzle erosion and is not to dissimilar to throat erosion in appearance.
From my experiences, 5 mm is the minimum barrel length i would remove after 400 shots on a magnum. The same 5 mm on a mid size cartridge after 600 rounds and with a small cartridge, 800 rounds is the line i cut at but maybe just 3 mm this time. The 6 BR as i said earlier is very abrasive on barrel crowns and i do re-cut after 400 rounds and remove about 5 mm.

Jethro Bodine.

That answers my question, no way im cutting back 5mm by hand

[Kenny]

Ohhhhhhhh I thought it was a finishing tool to use after you have lopped the barrel off.....

KY