Crowning A Barrel

[mauser]

Wow...sad quality there. Scary too

Have to wonder how thin it is at the headspace??

I was wondering the same thing. Is it off center at both ends or just at one end? It might be as accurate and consistent as any other but I'd have my doubts about safety with the wall being so thin on one side. (Even worse if the chamber is off center too, creating a thin/weak side).

[Bang]

That's how M1 Carbines and Garands got that worn at the muzzle, creating the need for the muzzle gauge when considering a purchase of one.

[Im not Batman]

The "crown" is the edge of the opening of the bore or the profile of the muzzle end of the barrel.

To recrown it is to recut it to improve the quality of the cut.
Crown is a noun, refering to the end of the barrel.
Crown is also used as a verb meaning to make a cut to refresh or reshape the actual crown.
A perfectly smooth and even cut is the desired condition of the muzzle end, (crown), of your barrel.
It isn't going to make a difference in ballistics if you're referring ballistics as muzzle velocity and muzzle energy, that's determined by bullet weight, size, shape, and fit in the barrel, barrel length, and the type and amount of propellant, (powder and primer combination). It isn't quite that simple, but that sort of covers the basics.
If you're thinking of ballistics as the performance of the projectile after it leaves the barrel, in terms of accuracy, you may notice a difference with recrowning if the original crown was damaged or of poor quality. If the crown is severely damaged, heavily worn or of very poor quality you will probably notice a marked improvement. Short distance, as in self defense pistol distance/range probably won't show much if any difference unless the damage/wear/quality is extremely bad.
As has already been stated, crowning evens out the muzzle to allow the gasses pushing the bullet to escape the barrel more evenly. If a straight cut barrel is perfectly cut and the gasses escape evenly around the bullet, that's as good as it's going to get. If there is any imperfection in the cut and the gasses escape unevenly it will have a direct affect on accuracy, and recrowning, (if done properly) should correct the imperfection(s) and improve accuracy. The "profile" of the "crown" is to protect the true crown, or the end of the bore. You'll notice that most crowns are recessed in some way;



But not these two:


Some are slight, some are extreme, some are not recessed at all.
Those that are straight leave the crown more susceptible to damage.
Whether radiused, straight cut with a recess or rebate, or counterbored, the intention is to have the opening of the bore slightly behind the absolute end of the barrel to protect the critical edge of that all important hole in the middle. Any metal protruding beyond the center hole will help to protect the edge of the bore, and that's where the bullet has it's last contact, therefore making it critical that that contact be as even and perfect as possible for best accuracy.
(Ever bump the end of your barrel on anything? A recessed crown helps to keep that unintentional contact from being on that critical edge.)
You can defeat the purpose of the recessed crown by cleaning your gun from the muzzle end, especially with a steel cleaning rod. Just rub one side with the cleaning rod while pushing in and out and the abrasion can cause uneven wear on the crown. Brass cleaning rods are better than steel and aluminum is better than brass, but cleaning from the breech end is best if possible.

Well OP...this is as good as it gets right here........^^^^^^^^^^

I look at the hack job on the 3rd photo and cringe...
I wonder if that person is working at GLOCK now??

[harold63]

After reading through that on the Glock forum I'm appreciating my Poofa pals even more.

You got that right.

[harold63]

Crowning the barrel?? Hey....auto racers have done LESS just for a 1/10 of a second gain

1/10 of a second times 200 laps = 20 second lead at checkered flag.


eta - in NASCAR, it don't matter 'cause someone gonna throw a screwdriver on the track to get a debris caution every time someone builds up a little lead.

[ChemDave]

Thanks to all for the information. I think I have the basics down. Is it safe to say that pistol barrels probably don't need to be crowned after market? I mostly target shoot but don't think I am at a level where I would need the last little bit of accuracy out of a handgun. And looking at the barrels that are not crowned under magnification none appear to have any irregularities that I can see. I learn something new all the time on this forum!

[sgtsandman]

I think barrel crowning is more of a rifle thing and for pistols that shoot rifle catriges. I don't recall much in the way of crowning on revolvers or semi automatic pistols. Not to say the condition of the muzzle on pistols isn't important.