Barrel crown question

[DIRTTRAX]

rdl65 or TiminTN or mrbig I saw were you both posted about the crown in the rem 700 accurizing post. What effect does it have or do to a gun? And what kind of crown do you prefer? I have read several articles that seem to contradict, and have always felt stupid for asking but heck with it I wanna know, lol. look foward to you answer.

 

[TiminTN]

The crown is the last thing that influences bullet flight. There is litterally tons of pressure behind the bullet as it exits. You want this pressure distributed as evenly as possible. If there is a crevice or flaw in the crown the pressure will be higher there as it acts like electricity and follows the least path of resistence. That uneven pressure disturbs the bullets flight. I don`t have a lathe, and have polished 2 of my match barrels with my broze mandrels after inspecting and seeing cleaning brush wear. Both of them are back to shootin like crazy.

 

[rdl65]

That's better than my explanation. I would of said if the crown is messed up your bullets aint gonna fly straight. lol

 

[DIRTTRAX]

So does the crown actually help, or does just the end of the barrel need to be perfect. For instance, if you have a gun with target crown and you cut the barrel off on a lathe and make sure its flat and theres no lip in the rifling. What will this change?

 

[TiminTN]

The crown just needs to be perfect. The different angles do not matter.

 

[mr.big]

old time BR shooters tell me the 11* crown is best for even pressure release around the bullet,,I don`t have the time with different crowns to say,,but every rifle I have shot with an 11 degree target crown shot VERY well.

 

[rdl65]

I would think if it's perfectly square it would be alright. Having a recessed crown protects it from damage though.

 

[TiminTN]

11* is old school 90* is where the benchrest smiths cut it. The angle is really insignificant.

 

[DIRTTRAX]

I would think if it's perfectly square it would be alright. Having a recessed crown protects it from damage though.

All the reading I have done has lead me to believe exactly what you stated here, more for protection than anything. Was just curious because everyone always mentions the 11 degree crown. As mr big stated have never tried anything to prove one way or the other. Either way im not a good enough shooter to know or see the difference if there was one. Its just a subject that gets discussed quite abit at work.

 

[mr.big]

the best 25 shot string I ever shot was with an old 40X single shot 222 magnum ,it had the 27 inch bbl cut with the 11* crown,and a 36XBR Leupold scope,,

I am sure as Tim says as long as it is good it wont matter,,but I admit I do think the old school stuff is cool,,

a friend of mine just came across a sleeved 40X 222 with a 21 inch bbl,Canjar trigger and 20X Lyman scope,I think the action is glued to the stock ,he says it is from the 60`s,

when the weather gets nicer he says he wants me to wring it out and see if it will still shoot,,I cant wait to try it..

 

[DIRTTRAX]

To me it would be a pleasure just to hold a 40x. have never seen one in person. What do you mean by sleeved 40x?

 

[mr.big]

they cut big aluminum cylinders that were kinda pressed over the action,in theory to make them stiffer,,this will be the first one I have shot..

 

[infoman jr.]

The crown is the last thing that influences bullet flight. There is litterally tons of pressure behind the bullet as it exits. You want this pressure distributed as evenly as possible. If there is a crevice or flaw in the crown the pressure will be higher there as it acts like electricity and follows the least path of resistence. That uneven pressure disturbs the bullets flight. I don`t have a lathe, and have polished 2 of my match barrels with my broze mandrels after inspecting and seeing cleaning brush wear. Both of them are back to shootin like crazy.

What he said.

An 11� crown is widely believed to be the most ideal for accurate shooting, but a more important factor is that your crown is concentric with the bore. If you look at how a lot of custom barrel makers do it, they'll hold the barrel in a 4 jaw chuck and indicate on the bore before cutting. They'll then cut the crown from the bore to the OD to prevent a burr from being rolled into the bore.

To true up a crown, several companies sell a piloted facing tool that follows the bore quite nicely.

 

[DaveB]

You can have the 90 crown so long as rifling is not touched, correct? I always thought that was the reason for crowning (In addition to protecting the rifling to some degree), to take the rifling clear to the end of the barrel but giving the gasses no room to escape until the bullet cleared the barrel.

If a 90 degree crown cuts through the rifling I don't understand/see the technical side of this improving accuracy.

 

[Encore Eye Candy]

I may be wrong but it has been explained to me that it is also based on what type of bullets you shoot, boattail vs flatbase. With a flatbase the crown allows the gases to escape around the bullet as it exits or clears the bore and with boattail gases escape without crown assistance. Again, I may be wrong.

 

[fastbs]

IMO and limited experience as long as the crown is clean with no burrs or imperfections and is concentric the degree of angle does not matter.

 

[TiminTN]

You can have the 90 crown so long as rifling is not touched, correct? I always thought that was the reason for crowning (In addition to protecting the rifling to some degree), to take the rifling clear to the end of the barrel but giving the gasses no room to escape until the bullet cleared the barrel.

If a 90 degree crown cuts through the rifling I don't understand/see the technical side of this improving accuracy.

Let me back up a step. The 11* is still a good crown for hunting and varmint applications where moving the rifle around may possibly allow the crown to get damaged. The 90* is widely used on target rifle applications. All crowns cut into the rifling. This cut just needs to be as clean as possible.

 

[TiminTN]

Here is an unfired Brux .243" bore chambered for a 6BRX. Fresh from my smith.

 

[FOX FIRE]

Anyone know of a good smith in the mid Tennarera that I can get to shorten & recrown a .243 barrel ???

 

[rdl65]

Here is the crown on my 243 that I had built by SAC.

 

[DIRTTRAX]

Sweet crown! If it works or not it looks good.

 

[rdl65]

I must say it works pretty good.

 

[DIRTTRAX]

Ive heard you mention that gun more than once. What about a pic of the whole setup?

 

[rdl65]

Here you go.

 

[Jksig229]

dang! that is slick

 

[DIRTTRAX]

Good god, im in love! Thats sweet. How you like the nightforce?

 

[rdl65]

I am very happy with it. I don't regret buying it one bit.

 

[jakeway]

My Ruger 260 shot like crap when I first got it...maybe 5" groups. Then I noticed a nick in the crown. Ruger offered to repair it,but the leadtime was longer than I wanted to wait. So I sent it to thegunsmith at Guns and Leather in Greenbriar. He re-crowned it in less than a week, only charged me $75, and now it shoots great.

Before:

Group:

After:

Group: (Don't get too excited...it's only three shots at only 50 yards.)

 

[rdl65]

That's a dramatic improvement Jakeway. Most people don't realize the importance of a good crown and why you need to protect it. And a cleaning rod can be it's worst enemy.

 

[DIRTTRAX]

That's a dramatic improvement Jakeway. Most people don't realize the importance of a good crown and why you need to protect it. And a cleaning rod can be it's worst enemy.

Do you use guides for the cleaning rods or just be extra careful? Ive got to where all I use is boresnakes.