Coning Question

[50cal.cliff]

I hear folks talking about coning their rifles. I know what it means and understand the purpose .
Once a barrel has been coned, in effect you have shortened the barrel. Or perhaps I should say the shortened the area where the rifling has (major) effect on the projectile. So here are my questions about a coned rifle.
How far back is a rifle barrel coned, in otherwords(how far should you be able to thumb start the ball)?
Has anyone had experience with coning a barrel and it effected accuracy?

 

[paulvallandigham]

The taper begins at the muzzle and gradually reduces over about 2-3" down the barrel. The coning only takes the lands down to Groove diameter at the muzzle, and as far back as it takes to seat a PRB so that the ball is below the level of the muzzle. Figure half the caliber of the bore. Even then, you can still see the lands at or very near the muzzle so your suggestion that the lands don't have any affect on the PRB is largely incorrect. Assuming that the coning is done square to the Bore, the gun should be just as accurate as it was before it was coned.

 

[faw3]

On my two I've had done they both just let the ball be thumb loaded as far as the end of muzzle so I'd say about 1/2 to a little over since my two are a 50 and 62 cal. And they shoot the same as before I had it done or so little different I cant tell. Fred :hatsoff: ( If youll look up coneing on here in Gen I think its been up here a few times the last 3 months Muzzloader magzine has run a test with a scoped rifle and all kinds of loads ect and showd it hurts over all but at a few points its better han the org barrel except the last of the 3 part thing they ran had a guy that did it by hand and small files his sure looked much better as each land and grove was hand filed. Makes for a great looking muzzle too!

 

[50cal.cliff]

Thanks for the info guys. The depth was about as I figured. I still do not see how it can not reduce the effect of the rifling in the coned area. This is how the desired thumb start is achived by grinding/filing the rifling away to facilitate that thumb start!
I know this has been discussed and after posting this discovered another post here in General Muzzleloading. I had origionally posted this in Muzzleloading Accuracy as that was one of my main concerns!
Has anyone on this forum coned a barrel and noted a reduction in accuracy? I would honestly like to know.

 

[Claude Mathis]

I still do not see how it can not reduce the effect of the rifling in the coned area.

In effect, all you have done is shorten the barrel by a half inch, as far as the ball making contact with the rifling. It has no effect on accuracy.

Has anyone on this forum coned a barrel and noted a reduction in accuracy?

I don't ever remember anyone posting that their gun was less accurate after coning. I could be mistaken.

 

[50cal.cliff]

OK guess we will put this one to bed then. Reduction in accuracy was my main concern. Primarily because it had been mentioned on another post that their had been tests done that showed it affected the accuracy!
The coned area is so small I guess it virtually has no noticable effect on the accuracy!!!!!

 

[Claude Mathis]

OK guess we will put this one to bed then. Reduction in accuracy was my main concern. Primarily because it had been mentioned on another post that their had been tests done that showed it affected the accuracy!

I'm not saying you can't improperly cone a barrel and screw it up. I've just don't remember anyone on the Forum saying that it effected accuracy in any way.

I did hear of an article in a magazine, that had some bad results, but I haven't read it and have no idea exactly what they did, so I can't comment on it. Perhaps someone else knows how they conducted their tests?

 

[50cal.cliff]

I may be incorrect about this but, I think it may have been Zonie that mentioned the tests, in a previous post.
If it wasn't you Zonie I apoligize in advance for putting your name into this discussion. Anyway maybe whoever it was could shed a little light on how they backed up those results in loss of accuracy!
I am considering coning my muzzleloader is one reason I was intrested in the accuracy concern. It would be nice to be able to thumb start a load if necessary. There is nothing more flustrating than to have to try and load a second shot and trying to short start a ball without making any noise.
Believe me been there and done that! Made a clean miss first shot :shake: and did manage to load second shot without spooking deer, but they were in the heavy brush by the time I managed to reload and cap! :wink:

 

[Zonie]

OK...As luck would have it, I can't find them, but I'll keep looking.

Several months ago, there were two articles in MuzzleBlasts dealing with conventional coning.
By conventional coning I'm referring to the cutting a very slight angled cone in the muzzle of the rifle. This cone is such that it removes the material down to the groove depth at the muzzle and tapers about 1-1 1/2 inches into the bore where it disappears leaving the full groove depth at that point.

I am not talking about the coning method where small round bottomed notches are filed into the lands of the rifling at the muzzle.

To test the effects of this on accuracy the author used a brand new barrel (as I recall, he actually did this on two different barrels of different calibers).

He built a dummy stock for the barrel and mounted a telescopic sight on it so that the sighting would not be an issue.
He then shot several targets with different loads and obtained the representative accuracy with these loads when fired in a un-modified barrel.

To assure that the newly machined cone would be exactly on center with the bore, he machined the taper into the barrel in a lathe after indicating the bore in to zero runout.

After machining the cone he then repeated the shooting to see if there were any effects either positive or negative on the barrels accuracy.

I can't give data because I cant find the damn magazines but the shooting showed that with some loads the accuracy was about the same.
With other loads there was a notable decrease in accuracy and as coning was the only thing that was done to the barrel the author came to the conclusion that this decrease was due to that process.

As I recall, the difference in accuracy was demonstrated however it was the kind of change that a marksman shooting in a competitive shooting match would not want to have in his gun, however it was not so great that a fairly good shot would notice much if any difference.
In other words, if you can hold a 1 inch group of 5 shots at 50 yards you probably will see a difference.
If on the other hand you typically shoot a 3 1/2 inch group at 50 yards you won't notice any change due to coning.

After reading these articles I came to the conclusion that the author did everything possible to be fair with the tests and to machine the barrels as accurately as is humanly possible.
He didn't have any apparent motive beyond simply finding out the effect of coning.

zonie

 

[paulvallandigham]

I agree: Coning if something to be done on a rifle that is to be used to hunt game, where the shooting is likely to be fast, off-hand, or from a standing rest.

If instead you are a target shooter, shooting primarily off the bench rest, then a coned muzzle is probably not going to be as accurate as one with a flat crown, that requires you to use a short starter to begin the ball down the barrel. Target shooters have all the time in the world to reload. Hunters, and warriors of old did not. Speed of reloading often meant the difference between living and dying.

 

[Don B]

I can't give data because I cant find the damn magazines but the shooting showed that with some loads the accuracy was about the same.
With other loads there was a notable decrease in accuracy and as coning was the only thing that was done to the barrel the author came to the conclusion that this decrease was due to that process.

Since the coning effectively shortened the barrel slightly, could the change in accuracy using certain loads simply be due to the fact that the shortened barrel's optimum load had changed?

Don

 

[50cal.cliff]

Thanks for the info Zonie. It leaves me with a little knowledge to mull over. At least I understand the test. If I am digesting the test info correctly. There was a differnce in accuracy but the difference was slight. Probably not noticealbe to the average shooter. :hmm:
Paul I agree with you. Sometimes and especially back when being able to load in a hurry could make all the difference!
Don, that's what I have been saying all along. Its long been know that a longer barrel on average is more accurate.
My Mother in law use to have a "Saturday Night Special" a .22 revolver with a 1" barrel.She bought it for protection. After I shot it one time I told her the best thing she could do was to stick in their ribs and pull the trigger. At any distance you couldn't hit accurately due to the short barrel and .22 shorts it shot!

 

[faw3]

I put it up I think when it (the first of 3 part test) came out in Muzzleloader in the last one the added another type of coneing by someone that semed to get really good after shots. Part 3 is in the July/ August one Zonie. If you belive the test then none of the old rifles could of ever beeen coned since most shots with the 50 cal and 60 to 70grs went about 6" off, or maybe that was good for back then? I dont think so, I have 2 done and they shoot as ood (done with a scope ) at 100yds as before they got coned. Whateverthey do load easy and if your hunting deer or whatever a 1' or 2' isnt going to be a big deal at 50 yds or so. Just My 2 Cents. FRED :hatsoff: (and I do belive the test was done right too , it just wasnt done on my barrels) Tryed to pull up the org post but its more than 6 months back now, it also seems to me they went way into the barrel and the one on mine is just enough to get the ball in more than 1/2 way with just your thumb vs a 1' or 2' the other way its done. A org Hawken was tested with its "coneing" 1/4" .0005 to .002 right at the muzzle and this rifle shot 20 shots in 50 yds in the black with 5shots 70grs,90grs,110grs,and 103 I think it was all inside 2"X2". I tryed to get a org type barrel made and no one had the time to even try to make one. So I guess you dont do it to target rifles but to anything else?

 

[50cal.cliff]

Thanks for the info. I was all set to do my .50 until I got to hearing about the test. In effect you have shortened (or shortened effective rifiling) in the barrel by a 1+". I honestly don't see this effecting the accuracy, but wanted to hear more on this test and how they achived the info.

 

[Zonie]

I really don't think the shortening of the effective barrel by one inch would cause a measurable difference in the accuracy of a gun providing the geometry of the muzzle or the bore was unchanged.

I can't prove it but I suspect the reason for a change in accuracy is due to "blow by" of the high pressure gas. This could occur as the patched ball reaches the area where the rifling lands have been removed due to the coning. Because there is no steel there, the patch becomes the only thing preventing the gas from blowing past the ball and any variation in the patch's weave or density would allow unequal amounts of the gas to blow past it.
If an unequal amount of gas does blow past the ball it will create a low pressure area in that zone and this could deflect the ball.

If I am correct, the effect would vary from shot to shot because it is impossible to predict where this patch blow by will occur.
I will also add that because the length of this leak zone is only an inch or so long and the ball is traveling at very high velocity the length of time would be short enough that a retrieved patch very likely would show no signs of burning.
(At a muzzle velocity of 1500 feet per second, the length of time for the patched ball to pass thru a 1 inch long coned zone is about 56 millionths of a second.)

The effect on the balls trajectory would be similar to that found and described by Dr. F.W.Mann in his book THE BULLETS FLIGHT FROM POWDER TO TARGET .
In this book, Dr Mann found that any defect or variation in the base of a bullet would affect the bullets flight path due to the unequal gas pressure loads acting on the bullet as it left the muzzle.

That's at least my guess.
zonie

 

[faw3]

As Zonie said the coneing isnt long, at least not on mine, just as deep as the cal say 50 cal is a little less than 1/2" 62 cal is 6/10th" if you keep it tight (the coneing) and you would have to ask on PT I guess on here how John Taylor how he did my first one I did the second the "old Muzzle Blast way with drill and round cutter a bit oversize and it worked great (put heavy cloth around cutter) I didnt nail down the table like they did in the test but used a "sniper scope on a underhammer and it was easy to load with no short starter and still rigth on target at 100 yds. Fred :hatsoff: "The effect on the balls trajectory would be similar to that found and described by Dr. F.W.Mann in his book THE BULLETS FLIGHT FROM POWDER TO TARGET .
In this book, Dr Mann found that any defect or variation in the base of a bullet would affect the bullets flight path due to the unequal gas pressure loads acting on the bullet as it left the muzzle." TRUEbut we dont have a flat based bullet here, the center of the ball is all thats touching, Im sure if you do it like Hawken did "Just .0001 th of a inch you'll do fine.

 

[50cal.cliff]

Thanks for the info again everyone.
Zonie let me ask a couple of questions about your last post.
If I am understanding correctly. In other words on a barrel that hasn't been coned you will get an even release of the gases at the end of the barrel.
The blow by, you are speaking of is caused by an uneven release of gases an the end of the muzzle! On a coned barrel the gas release is not all at once because of that last 1" or so!
If I am correct in that assumption ,the final release of gases will be slightly gradual, instead of immediate release. Kind of like the pop you would get pulling a cork from a jug. If you were to relieve the inside of that opening (like coning), you would not get that loud pop!
Could the results of the tests been caused by a bad coning job?
Is that an inherit characteristic of coning, (the blow by)?
If a proper coning job is done, do you feel this effect would be minimal on the accuracy?

 

[faw3]

Could the results of the tests been caused by a bad coning job? Let me jump in again since I reread all 3 parts again last night and may be off and in hospital for a few days. They couldnt of done a bettr job of doing it. This was a pro jod. Now for the BUT!! You have to read all 3 parts because in the first and part of second the "coned" out shot the unconed, it depended on Lube,Powder charge,AND Bore size! to get to the 3rd part. If you look at the pics in all 3 I still have never seen a coneing or any of the other things tryed that took out all the LANDs up to the muzzle - maybe thats why the org Hawken could shoot 20 shots into such a small target at 50 yds and it didnt matter what amount of powder they used. The3y did use 200 gr loads and still hit what they aimed at at 100 to 200 yds "sometimes" more than not. It seems that the smaller bores get really messed up by doing anything with them, while Swiss outshot even the unconed bigger bores till you got up to bigger charges. See it aint all black and white BUT was a good test, Try ..say you have 50 cal shooting 5 shots with spit and 495 ball then do the same with 490 and 80 or more powder and see what you get? ( I did last night ,even went with a smaller ball,( OH 015 Patch on alll of these and lots of spit) see how hard to easy it loads and what do you think. They did say the patchs seemed to be a problem,some more than others burned bad I'll have to get my kid to ck out mine since I cant walk all over the place and we did shoot about 80 shots till it got dark with the coned but lands showing and a stock barrel. Also they do say something about after coneing they couldnt be sure about scope be lined right once again. Ok my 2 cents , got to go Best thing to do is read it your self and ck the pics, and Zonie will clear up what I may have missed along with what he got out of it. Again all I can say is the one John Taylor did for me the ball goes in easy and it shoots just as good (backed up with scope fire too) but as the Hawken was made the lands still show to end of muzzle. Fred :hatsoff:

 

[50cal.cliff]

Thanks for the great info Fred and hope everything goes well for you!
Ok lets say the coning job was done correctly. Are they shooting the same grain of powder and ammo they were in the rifle before it was coned?
Sounds like they changed up powder and grain of powder.
If a rifle has a sweet spot, and I belive they do. If you change powder and grain you will have to find that sweet spot again for accuracy, using the new powder and finding the right grain!
Could that why they were getting different results?

 

[Zonie]

I think fw pretty much hit the nail on the head.
A number of different loads were shot both before and after the coning and every effort was made to duplicate all of the loads without changing anything except adding the cone. The powder and patches were the same.

As fw mentioned the author had to remove the scope to machine the barrels and then reinstall it after the machining was done but, the author was not trying to see if the gun would still hit the exact same place after the scope was re-installed.
He was only concerned with the size of the groups.
Put another way, if the unaltered barrel was hitting an inch high with one powder load and the extreme spread was 1 inch before coning it would have been recorded as a 1 inch group. After removing the scope, machining the cone, reinstalling the scope and re-shooting the barrel with exactly the same powder/patch load it was hitting 2 inches low and to the left but the extreme spread of the group was 1 inch, he would have recorded the group as a 1 inch group.
That way, the reader could see that with that powder load coning did not affect the accuracy.

As for my thoughts on why coning might affect accuracy it is only a theory and is without proof.
fw did remind me though that the author of the article did notice that with some loads in some calibers the patches were blown all to H. I had forgotten that but it could add some weight to the idea that for some reason gas was blowing past the patches and as I said, if this blow by was not evenly distributed around the circumference of the bore it could deflect (ever so slightly) the path of the ball.

zonie