When a rifle needs a crown?

[Colo-PR]

Hi guys,

Im barely new to precision shooting and last year I bought a Savage 12 Benchrest model (http://www.savagearms.com/firearms/model/12BENCHREST) . I been doing the load development for about a year and I still don't find the load he likes. I got everything Redding with a T7, tried all kinds of powder, tried from 2k from lands up to 10k and nothing to impress, im getting the same results as I get with a simple Ar-15.

Last night I decided to meticulously check the muzzle of the rifle for any defect from factory when I realized that the barrel dont have a crown. I mean, the barrel is not flat in the front, has the recess bot not a crown and now I wonder, do every rifle needs a crown? Everything I found online says that a crown improves accuracy but maybe in 6mmBR caliber not? Should I make him one (with the appropriate tools of course) or this type of rifle don't need it?

I shoot benchrested in an indoor range at 100 yards.


The muzzle of my barrel is something like this: https://www.pyramydair.com/blog/wp-...-Butler-Creek-bull-barrel-for-10-22-crown.jpg

Thanks in advance

 

[Terry]

The recess is the crown.

 

[dmoran]

That is a "recessed crown", which is what @Terry said: "the recess is the crown", that is recessed to protect the crown from being bumped, nicked, etc..
Donovan

 

[Stan Taylor]

Hi guys,

Im barely new to precision shooting and last year I bought a Savage 12 Benchrest model (http://www.savagearms.com/firearms/model/12BENCHREST) . I been doing the load development for about a year and I still don't find the load he likes. I got everything Redding with a T7, tried all kinds of powder, tried from 2k from lands up to 10k and nothing to impress, im getting the same results as I get with a simple Ar-15.

Last night I decided to meticulously check the muzzle of the rifle for any defect from factory when I realized that the barrel dont have a crown. I mean, the barrel is not flat in the front, has the recess bot not a crown and now I wonder, do every rifle needs a crown? Everything I found online says that a crown improves accuracy but maybe in 6mmBR caliber not? Should I make him one (with the appropriate tools of course) or this type of rifle don't need it?

I shoot benchrested in an indoor range at 100 yards.


The muzzle of my barrel is something like this: https://www.pyramydair.com/blog/wp-...-Butler-Creek-bull-barrel-for-10-22-crown.jpg

Thanks in advance

I would like to see a picture of your crown

 

[gunsandgunsmithing]

Every barrel has a crown but some are better than others. Flat, recessed or target crown, makes no difference, but you want a good, sharp and concentric crown, where the bullet exits, for best accuracy.

 

[foxguy]

Which caliber did you buy. I purchased one of the F-class models in 6MM BR and it shoots very well when I do my part.

 

[kneedtospeed]

 

[Stan Taylor]

View attachment 1040018

Haha haha

 

[Dusty Stevens]

tell us about your rest setup. this sounds like the problem in this case but whatever issue you have we can fix given enough info. welcome to the forum BTW

 

[rckendall]

Hi guys,

Im barely new to precision shooting and last year I bought a Savage 12 Benchrest model (http://www.savagearms.com/firearms/model/12BENCHREST) . I been doing the load development for about a year and I still don't find the load he likes. I got everything Redding with a T7, tried all kinds of powder, tried from 2k from lands up to 10k and nothing to impress, im getting the same results as I get with a simple Ar-15.

Last night I decided to meticulously check the muzzle of the rifle for any defect from factory when I realized that the barrel dont have a crown. I mean, the barrel is not flat in the front, has the recess bot not a crown and now I wonder, do every rifle needs a crown? Everything I found online says that a crown improves accuracy but maybe in 6mmBR caliber not? Should I make him one (with the appropriate tools of course) or this type of rifle don't need it?

I shoot benchrested in an indoor range at 100 yards.


The muzzle of my barrel is something like this: https://www.pyramydair.com/blog/wp-...-Butler-Creek-bull-barrel-for-10-22-crown.jpg

Thanks in advance

If I am reading this correctly, you are saying that you tried seating depths at .002-.010 off the lands. If that is correct you may need more jump. I shoot Berger Hybrids in a couple different calibers and mine seem to like .025-.030 off the lands. I've read that some need more.

Richard

 

[Colo-PR]

Hi guys, sorry for the late reply, for some reason I was not getting the notifications.

I tried 0.002, 0.003, 0.004, 0.005 etc until 0.010

Is a 6mmBR

Lapua cases

So far I tried IMR4895, N135, Varget, N140, N540, RE15. So far the best result I got was with 24g or Varget at 0.005 off the lands but was not touching each other or if 2 touched the third shot not.

So, going back to the crown, now that I learned that a recessed as the picture I put the link is a crown that kinda no make sense for me in terms that should not be the same result. In the crowns I saw online, in videos and some of the other rifles I own the crown is in an angle (I don't know if is 45 degrees or something like that) but an angle crown should have the same results as a recessed crown? Kind of no make sense how the gases excape, in the angle crown the gases can leave the barrel while part of the bullet still in the barrel but in the "recessed crown" dont look like the gases excape until the bullet is completely in the air.

Should I get any benefit if I make an angle crown on top of the recessed one?

I plan to try next week some Lapua 105g factory ammo that I seated to 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 etc to see what happens.


Attached is a picture of the actual crown of my rifle.

 

[gunsandgunsmithing]

Hi guys, sorry for the late reply, for some reason I was not getting the notifications.

I tried 0.002, 0.003, 0.004, 0.005 etc until 0.010

Is a 6mmBR

Lapua cases

So far I tried IMR4895, N135, Varget, N140, N540, RE15. So far the best result I got was with 24g or Varget at 0.005 off the lands but was not touching each other or if 2 touched the third shot not.

So, going back to the crown, now that I learned that a recessed as the picture I put the link is a crown that kinda no make sense for me in terms that should not be the same result. In the crowns I saw online, in videos and some of the other rifles I own the crown is in an angle (I don't know if is 45 degrees or something like that) but an angle crown should have the same results as a recessed crown? Kind of no make sense how the gases excape, in the angle crown the gases can leave the barrel while part of the bullet still in the barrel but in the "recessed crown" dont look like the gases excape until the bullet is completely in the air.

Should I get any benefit if I make an angle crown on top of the recessed one?

I plan to try next week some Lapua 105g factory ammo that I seated to 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 etc to see what happens.


Attached is a picture of the actual crown of my rifle.

Don't over think the crown thing. It has been proven that different crown styles work equally well. The crown has two jobs...clean release of the bullet and protection against damage.

There are theories about gasses and crown design but they have all won too many BR matches to discount or proclaim a certain style as better or worse than another. The important thing is that it be clean and perpindicular to the bullet axis. This should aid in respect to gasses but moreso, in the bullet releasing all the way around at exactly the same time.

Various muzzle devices, such as brakes, tuners and suppressors are all generally seen as accuracy enhancements. If gas was the issue of importance, none of them would work well for accuracy. Again, there are theories about which is the best style but they are just theories until one starts winning consistently over the others..

In regard to jump to lands...a lot of guns prefer some amount of jam rather than jump. Post some group pics. We can better evaluate things with more to go on. What loads are you shooting, too?

 

[DanSavage]

Hi guys, sorry for the late reply, for some reason I was not getting the notifications.

I tried 0.002, 0.003, 0.004, 0.005 etc until 0.010

Is a 6mmBR

Lapua cases

So far I tried IMR4895, N135, Varget, N140, N540, RE15. So far the best result I got was with 24g or Varget at 0.005 off the lands but was not touching each other or if 2 touched the third shot not.

So, going back to the crown, now that I learned that a recessed as the picture I put the link is a crown that kinda no make sense for me in terms that should not be the same result. In the crowns I saw online, in videos and some of the other rifles I own the crown is in an angle (I don't know if is 45 degrees or something like that) but an angle crown should have the same results as a recessed crown? Kind of no make sense how the gases excape, in the angle crown the gases can leave the barrel while part of the bullet still in the barrel but in the "recessed crown" dont look like the gases excape until the bullet is completely in the air.

Should I get any benefit if I make an angle crown on top of the recessed one?

I plan to try next week some Lapua 105g factory ammo that I seated to 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 etc to see what happens.


Attached is a picture of the actual crown of my rifle.

How far up did you go with Varget powder? 24gr. is very very low for a 105 bullet.

 

[newbieshooter]

Hi guys, sorry for the late reply, for some reason I was not getting the notifications.

I tried 0.002, 0.003, 0.004, 0.005 etc until 0.010

Is a 6mmBR

Lapua cases

So far I tried IMR4895, N135, Varget, N140, N540, RE15. So far the best result I got was with 24g or Varget at 0.005 off the lands but was not touching each other or if 2 touched the third shot not.

So, going back to the crown, now that I learned that a recessed as the picture I put the link is a crown that kinda no make sense for me in terms that should not be the same result. In the crowns I saw online, in videos and some of the other rifles I own the crown is in an angle (I don't know if is 45 degrees or something like that) but an angle crown should have the same results as a recessed crown? Kind of no make sense how the gases excape, in the angle crown the gases can leave the barrel while part of the bullet still in the barrel but in the "recessed crown" dont look like the gases excape until the bullet is completely in the air.

Should I get any benefit if I make an angle crown on top of the recessed one?

I plan to try next week some Lapua 105g factory ammo that I seated to 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 etc to see what happens.


Attached is a picture of the actual crown of my rifle.

There are several shooters at our club matches that shoot the Savage 12F 6BR. For Varget their loads are in the 28.0gr-29.0gr range with 105 class bullets.

 

[Dusty Stevens]

Your crown isn’t the problem. You can hacksaw it and it’ll still shoot better than that. Check your rest setup and use and understand wind flags. A bad crown makes a .250 group a .252. When you can see that kind of resolution then worry about the crown.

 

[hogpatrol]

I remember a test that was posted online about a rifle that was crowned with a hacksaw and it shot almost the same as when it had a machined crown. Still googling for it.

 

[josh shrum]

Hi guys, sorry for the late reply, for some reason I was not getting the notifications.

I tried 0.002, 0.003, 0.004, 0.005 etc until 0.010

Is a 6mmBR

Lapua cases

So far I tried IMR4895, N135, Varget, N140, N540, RE15. So far the best result I got was with 24g or Varget at 0.005 off the lands but was not touching each other or if 2 touched the third shot not.

So, going back to the crown, now that I learned that a recessed as the picture I put the link is a crown that kinda no make sense for me in terms that should not be the same result. In the crowns I saw online, in videos and some of the other rifles I own the crown is in an angle (I don't know if is 45 degrees or something like that) but an angle crown should have the same results as a recessed crown? Kind of no make sense how the gases excape, in the angle crown the gases can leave the barrel while part of the bullet still in the barrel but in the "recessed crown" dont look like the gases excape until the bullet is completely in the air.

Should I get any benefit if I make an angle crown on top of the recessed one?

I plan to try next week some Lapua 105g factory ammo that I seated to 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 etc to see what happens.


Attached is a picture of the actual crown of my rifle.

Colo,

Read up on what pressure signs look like. Then read a whole lot more on what pressure signs look like. Then read up on what are popular loads for the 6BR, reduce them by 10% and work up slowly to those popular loads, watching for those pressure signs you read about the entire time.

You seem to be really low on your Varget load, as in well below the 10% reduction.

As Dusty said, make sure that your rest/bags are not inducing any error into your shooting.

Same with the bench.

Couldn't hurt to make sure the scope is properly mounted as well, we have all made that mistake (well, most of us )

As for your crown...

The crown is merely the point where the bore ends.

Checking your crown for actual damage is a good thing, I do it at the beginning of each season, or if you happen to bang/bump the muzzle into something.

It is incredibly unlikely that your barrels crown is the culprit in your big groups.

Josh

 

[gat]

Damaged or bad crowns cause fliers!

 

[6MMsteve]

rebarrel it with a Kreiger or Brux and it will shoot great imho please and you will be hapy

 

[Dusty Stevens]

Damaged or bad crowns cause fliers!

Are you sure? If you dented your freshly hacksawn crown with fguffeys hammer and punch right across one side- wouldnt that affect every shot? Or does 4 just sneak on by and that pesky 5th shot flyer raise its ugly head? I personally hate 5 shot groups i think we should go to 2 shot groups