Crowns

G

geocole

Guest
Which is best for target shooting
11 degree crown
Recessed crown
 
While on the subject of crowns

How often should a match grade barrel be recrowned if brass brushing is not used?

Lou Baccino
 
Lou ...

How often? When it needs it. Here's a way to determine if it really needs it. Take a cotton swab / Q-tip and run it in and out all around the interior end of the barrel. If there's a burr anywhere, caused by any number of reasons, the cotton on the swab/Q-tip will catch on it. If you see that happen, it's time to recrown. :)
 
Re-crowning

abintx said:
How often? When it needs it. Here's a way to determine if it really needs it. Take a cotton swab / Q-tip and run it in and out all around the interior end of the barrel. If there's a burr anywhere, caused by any number of reasons, the cotton on the swab/Q-tip will catch on it. If you see that happen, it's time to recrown. :)
Click to expand...

That's a good tip. I know some routinely re-crown after a given number of rounds but I stopped using a brass brush awhile ago, preferring a nylon brush with Wipe Out and Accelerator.

I saw an example today of a crown that was cut with a ceramic insert and the surface finish was incredible.

Lou
 
Lou

Ceramics need extremely fast RPM and stiff set-ups to be effective. Many of the lathes used by Gunsmiths are compromised in these departments.

The requirement of a crown is it be square with the bore, and free of any burrs.

That term 'square with the bore' is in many cases assumed. In actuallity, what that means is square with what ever length that the body of the bullet sees as it exits. Try indicating a 1/4 inch length to the nearest .0001.

I go back to a truth that has always bugged me. We strive to make every piece of machine work involved in barrels, and actions, to the tiniest of tolerances. The, we insert ammunition that runs out as much as .002-.003 inch. When that case is chambered, it becomes part of the package. Or, at least you would think.........jackie
 
Ceramics

jackie schmidt said:
Ceramics need extremely fast RPM and stiff set-ups to be effective. Many of the lathes used by Gunsmiths are compromised in these departments.

The requirement of a crown is it be square with the bore, and free of any burrs.

That term 'square with the bore' is in many cases assumed. In actuallity, what that means is square with what ever length that the body of the bullet sees as it exits. Try indicating a 1/4 inch length to the nearest .0001.

I go back to a truth that has always bugged me. We strive to make every piece of machine work involved in barrels, and actions, to the tiniest of tolerances. The, we insert ammunition that runs out as much as .002-.003 inch. When that case is chambered, it becomes part of the package. Or, at least you would think.........jackie
Click to expand...

Jackie,
Thanks for the input. This gunsmith you probably know, as do many; he's been in the game a long time. I don't know what speed he used but the crown was very sharp with no observable tooling marks; it looked like glass. He has two of my Kreiger barrels that are being chambered.

Lou
 
chino69 said:
Jackie,
Thanks for the input. This gunsmith you probably know, as do many; he's been in the game a long time. I don't know what speed he used but the crown was very sharp with no observable tooling marks; it looked like glass. He has two of my Kreiger barrels that are being chambered.

Lou
Click to expand...
Lou, while a smooth and shiny surface finish of the barrel face looks nice it is not the important aspect for best accuracy. Perfectly concentric bevel to bore intersection, if there is a bevel or an 11 degree, and perfectly burr free intersection of the two surfaces are musts.
 
Crown

JerrySharrett said:
Lou, while a smooth and shiny surface finish of the barrel face looks nice it is not the important aspect for best accuracy. Perfectly concentric bevel to bore intersection, if there is a bevel or an 11 degree, and perfectly burr free intersection of the two surfaces are musts.
Click to expand...

Jerry,
I agree with the above but it's a double treat when precision also looks nice. I spend time looking at the bore of a match grade barrel with a borescope in appreciation of the work that went into a hand lapped bore.

Lou
 
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