Barrel Crown...what is it exactly?

[FlinchNJerk]

I've read and heard a lot about "make sure the barrel crown doesn't have any nicks or burrs in it" as this reduces accuracy.

I'm confused as to what exactly is the barrel crown. Is it the entire end of the muzzle? Or is it just the very small recessed area where the bullet exits? Here are some pictures to hopefully clear up my question.

This is my rifle...does the paint on the muzzle have a negative effect on accuracy? Also mine does not have that recessed area like the picture above does, well it does it's just very small.

 

[squirrelduster]

Hey Flinch,
Your crown on the lower picture could cause you problems. You should take all of the paint off of the end of the barrel it might not let the bullet exit correctly.
Your red arrow and white are both the crown. Some smiths will do a two step system like the one in the top picture. The purpose is for the bullet to clear the barrel on a sharp edge and get the same release every time.

 

[vmthtr]

I wouldn't worry about the paint. Bullet is gone by the time it would affect the flight.

Mike

 

[BoydAllen]

The place that is referred to in the advice that you mentioned is the actual edge where the bore ends. It is also true that the entire end, out to the corner where it meets the side of the barrel is called the crown. Because of ease of production, and the sheltered life these rifles lead, many Benchrest crowns are at 90 degrees to the bore with no recess or chamfer. The chamfer or recess that are so common are designed to protect the edge of the bore.

 

[jwv2001]

I re-indicated the crown in your photos. The crown should be perfectly square with the bore and the edge should be sharp and clean. If you place a bullet in the bore, everything the bullet touches is the crown. Care should always be taken to keep the crown protected from damage.

 

[rcw3]

Seems like som mis-definitions here. The "crown" refers to the entire end of your barrel,not just the intersection of where the crown meets the bore). For example an "11 degree crown" refers typically to the end of the barrrel machined at an 11 degree angle, this may be sharp at the bore or have a 45 degree chamfer, etc.

The top photo you have indicated looks like it is an 11 degree crown with a 45 degree chamfer at the edge where it meets the bore. That being said, it is really the edge of the crown,where the crown intersects with the bore) that is spoken of to have the most effect,good or bad) on accuracy.


Robert Whitley

 

[jwv2001]

The crown is the edge of the bore where the rifling exits the muzzle. It doesn't matter how you choose to recess the crown, i.e. 11° or whatever, the crown is still the crown.

 

[Forum Boss]

From MidwayUSA Gun Dictionary:

1. Definition for "crown" : The shaping of the point on a muzzle where the end of the bore intersects with the face of the end of the barrel. A variety of different styles and shapes of crowns have evolved to meet specific shooting needs. Maintaining uniformity and consistency of the crown is important as this is the last point of the bore that the bullet contacts as it exits the barrel.

MODERATOR: The above suggests that the crown embraces more that just the edge of the bore, at least when one speaks of what is done during "crowning". See below.

1. Definition for "crowning" : A barrelmaking/barrel-improving technique in which the bore edge at the muzzle is either beveled or slightly recessed. This strict uniformity of the cut insures that no unbalanced force acts upon the bullet as it leaves the barrel and creates a flawless exit area for the bullet, while the bevel or recess helps keep the crown undamaged from careless handling.

----

Many manufacturers referred to the type of muzzle shown below as a "recessed crown" or "target crown". The recess, of course, refers to a zone extending beyond the edge of the bore.

Alan Warner, who is one hell of a gunsmith, also calls a muzzle-facing like the above a "recessed crown". However he distinguished this from the edge of the bore by calling that the "actual crown". See: http://www.warner-tool.com/Custom%20Rifle.htm

Confused yet??

So, in some applications, the word crown refers to the charactistics of the muzzle face. In other situations, as when someone says they have a "burr on the crown" they are probably referring to the actual front edge of the bore,the last metal the bullet contacts on exit).

I think we need to accept that "crown" is used multiple ways and that the terminology lacks precision. Perhaps in German there is a specific word,other than "crown") to describe the actual edge of the bore at the muzzle and ONLY the edge of the bore.

 

[DukeDuke]

Why does it matter? Convex crown anyone?

 

[tightneck]

Why does it matter? Convex crown anyone?

It doesn't. What matters is that the crown is sharp, and indicated with the bore. The only problem with a convex crown is it's lack of protection.

 

[FlinchNJerk]

Thanks for the insight guys. I have a good grasp on what the crown actually is now :]

 

[Twud]

The reason the crown is so important is that it's the last place the bullet touches the bore. If it is damaged or irregular in any way it will impact the bullet's path. The recess, however you cut it, is to protect this area. It's probably more important on a field rifle than a BR gun. Your second picture with the paint would likely not effect accuracy as long as none of it touches any port of the bore.
The crown on my bench gun is so sharp you can cut a patch while cleaning.