Crown on target rifles

[BradY]

Can I ask those experienced machinists if possible, what style of crown do you do for BR and f class rifles?
In my group of shooters, there seems to be a few that will use a deep bore the crown an inch into the muzzle then finished with an 11 degree crown, then those that run a standard 11 degree cut at the muzzle, then finally those who run a flat 90 degree crown.

 

[Larryh128]

I've done all of them & really don't see any difference, mostly personal preference. My favorite is the recessed 11 degree mainly because I think it looks cool. I see no accuracy difference over a straight 11 degree. Big deal is making sure it's indicated in properly.

 

[X Ring Accuracy]

We do a recessed square crown. As stated, the most important thing is concentricity....hope that is a word : )

 

[jscandale]

Heck, everyone knows that the most accurate crown is a recessed 11° square crown. Duh!
I think this same thread gets duplicated more times than an actual crown does.

JS

 

[Grimstod]

If your crown has runout your bullets will be more prone to key hole. This is assuming your bullets are not stable using too. That's about the only accuracy problem you will see right away. It biggest perpose is to protect the rifling and control how the gasses exit behind the bullet. It is very important to get right. Had a bad one once after it was fixed by another smith that was more competent it shot twice as good.

 

[ridgeway]

What do you mean by runout?

 

[butchlambert]

I'm confused also.

 

[Grimstod]

Sorry I should have said trued up 90degres to the bore axes. I am on my phone this week cause no internet so my post have been sloppy.

 

[Alex Wheeler]

Rrrrright. Anyways...
I am no smith but I prefer a 90 degree crown because it is the easiest for the smith to get perfect. If your cutting a cone of any angle it has to be perfectly concentric to the bore, much easier to be slightly off than 90. I always specify a 90. But I think it has been covered enough that if done correctly you wont be able to tell the difference.

 

[Scott Harris]

Rrrrright. Anyways...
I am no smith but I prefer a 90 degree crown because it is the easiest for the smith to get perfect. If your cutting a cone of any angle it has to be perfectly concentric to the bore, much easier to be slightly off than 90. I always specify a 90. But I think it has been covered enough that if done correctly you wont be able to tell the difference.

I've heard this reasoning before and not sure I agree. If the bore is out of alignment, then any crown you cut will be off. If it is dialed in properly, then any crown you cut will done properly.

 

[Erik Cortina]

Rrrrright. Anyways...
I am no smith but I prefer a 90 degree crown because it is the easiest for the smith to get perfect. If your cutting a cone of any angle it has to be perfectly concentric to the bore, much easier to be slightly off than 90. I always specify a 90. But I think it has been covered enough that if done correctly you wont be able to tell the difference.

If its setup properly it does not matter what the crown looks like, it will be square to the bore. Concentricity does not matter.

90° or cone requires the same setup. One is not easier to get "right" than the other.

 

[Macropod]

There is a big difference between an 11 degree crown and one that is squared off if the barrel set up in the lathe isn't perfect...

The 11 degree crown will suffer a lot more if concentricity isn't perfectly dialled in.

Either will work fine if the 'smith knows his stuff.

 

[Raythemanroe]

Rrrrright. Anyways...
I am no smith but I prefer a 90 degree crown because it is the easiest for the smith to get perfect. If your cutting a cone of any angle it has to be perfectly concentric to the bore, much easier to be slightly off than 90. I always specify a 90. But I think it has been covered enough that if done correctly you wont be able to tell the difference.

I've heard this reasoning before and not sure I agree. If the bore is out of alignment, then any crown you cut will be off. If it is dialed in properly, then any crown you cut will done properly.

Shouldn't you be indicating from the bore?

 

[skeetlee]

I had as well worn, but still very accurate 6ppc barrel here at the shop that I decided to do a little test with.
The crown looked a little worn so I chucked this barrel up in my 3 jaw chuck an simply faced the crown with a good sharp tool. I took the barrel out back an it shot a .200 flat 5 shot group. I thought I better try that again. I shot another .264 group, an then another .230
I then went back into my machine shop an set the barrel up properly in my 4 jaw an indicated everything in the best I could. I again faced the barrel with the same sharp tool I used before.
I went back out to my range an shot 3, 5 shot groups that average .257 or 267 cant remember for sure . conclusion? I am going from memory so my numbers are the best I can remember," they are close" but what I do know, is that what little testing I did, didn't show me what I thought I would have seen. Of course I always indicate my crowns, but I still cant help but think about this little test I performed. Lee

If anyone needs to know my 3 jaw shows .0015 total run out on the dial. pretty close for a cheap 3 jaw.

 

[X Ring Accuracy]

To be clear on my post. I said concentric, which would mean I dial in the bore, my mistake. What I should have said is square to the bore. If the crown is square you are eliminating a variable which is what the pursuit of accuracy is. Like Skeet said, he recrowned a barrel 2 ways and got good results. Will a bedded rifle outshoot a non bedded one? Certainly, but to what degree? Its all about removing what ifs and the nut loose behind the trigger.

 

[jonbearman]

He asked this question last november.I doubt he is reading our thoughts.But he did ask a legitimate question and regardless if it has been beat to death with answers,the simplist answe is to answer instead of insulting the guy right off the bat.A dialed in crown is a dialed in crown.It is all a matter of preference.I like an 11 degree crown because it looks nice.Would a flat crown work,absolutely,but in the end it doesnt matter the shape as long as it is as square as we can make it.

 

[Raythemanroe]

He asked this question last november.I doubt he is reading our thoughts.But he did ask a legitimate question and regardless if it has been beat to death with answers,the simplist answe is to answer instead of insulting the guy right off the bat.A dialed in crown is a dialed in crown.It is all a matter of preference.I like an 11 degree crown because it looks nice.Would a flat crown work,absolutely,but in the end it doesnt matter the shape as long as it is as square as we can make it.

I like the 11 degree type crown also, It looks better..

Ray