Problem with Coned barrel

[SR James]

I recently picked up a nicely built .40 flinter. The gun showed very nice craftsmanship but my first range experience with it was very disappointing. I played with .395 and .400 diameter balls, patches from .015, .018, and .020 and even denim that is at least .022. POI was all over the target at 50m. No groups at all. Fired patches were normal, seating effort was normal. It was when I went to what should have been a very tight combo that I realized that short starting the ball was still quite easy, while the ramming effort was very tight. Taking the rifle out into the sunlight from under the range cover showed why...the muzzle is coned.
This is my first experience with a coned barrel. My first thought is to cut the muzzle back past the coning and recrown. But thought I'd ask the forum for other possible suggestions first. Any thoughts?

 

[nkbj]

That'd be interested to look at. Would it be possible to post a close up photo?

 

[ApprenticeBuilder]

I personaly would never cone a barrel, though the accuracy of a coned barrel may be almost as good as a non-coned barrel provided the job was done correctly.

A poorly coned barrel would be a mess. :shocked2: such as you describe.

But in all fairness we need alot more information to make a solid assesment.

Patch lube, type of rest, poured or bought balls, etc.

 

[Rifleman1776]

Don't get out the hacksaw yet. :shocked2:
You are to be commended for trying to develop the best ball/patch combo for your new gun.
I suggest you keep working on finding the best ball/patch/lube/charge combo for your new rifle.
Lotsa things could be factors. Are you using pure lead soft round balls? What kind of lube? What kind of powder and what charges? Those small calibers can be fussy.
My wife has a nice custom built .40 perc. Recently I tested it for group and dropped from 40 gr. Goex 3Fg to 25 gr. Swiss 3Fg and groups tightened up very nicely.
This is the bp, muzzle loading game. We ain't working with exacts of nuttin' .

 

[Robby]

I would first do a Rifleman said, and try any and all possibilities and combinations. Coning is a manure shoot, sometimes you win, sometimes you loose, and when you loose, its big time. I will never understand the practice.
If you have a real nice gun and cut off the coning it will throw off all the proportions built into the gun requiring, at least moving pipes around and installing a new nose cap. Another solution might be to have it counter bored to just below the coning and carefully re-crown. About the only loading difference would be using pre-cut patches. What kind of barrel is it?
Robby

 

[necchi]

A poorly coned barrel would be a mess. :shocked2: such as you describe.

That's true enough,
But it's also true that done properly a coned barrel does no harm to a good shooting barrel or a good shooter.
I have a few that are coned and they're fine.

If your determined to cut it, unless your a machinist, I'd have someone with a lathe cut and re-crown your barrel.

 

[SR James]

Thanks for the replies. More information:
I'm an very experienced muzzleloader shooter(since the 70s). I have a lot of muzzleloaders in all calibers; rifles, smoothies, etc. I say this just so you'll know I'm not a beginner. Not that I can't learn new stuff, but I've never had a rifle give me problems like this one.
For the record, the barrel is by Green Mountain. I was using Goex 3Fg, charges varied from 30 to 60grs in 5gr increments. The .395 balls were Hornady, the .400 were hand cast of pure lead from Track . Some of the patches were pre-cuts but I also muzzle cut some material that I have used with good results in other rifles. Patch lube was Hoppes 9+ which I've used with good results in many rifles. The rifle was shot from the bench in a rest made by Target Shooting, Inc. at 50m. I followed the same procedures using the same materials as I've done with many other rifles in working up loads. Not one single combo in this particular rifle produced anything resembling a group. Out of five shots, two might be within 3" but the rest scattered over 6-8" or more. The only thing different about this rifle from the many others I've shot is the coned muzzle.

 

[necchi]

Well that covers it.
My guess then is your right, it's a botched coning job, blowing shot's 6-8"s at 50 is a sign something is serious wrong.
The Feller must have wobbled the tool bad when he did the coning job, maybe used a drill instead of going slow by hand, :idunno:

 

[wattlebuster]

Sounds like ya know what your doing as far as shooting an working up loads so I will have to go with necchi on this one an say it MIGHT be a bad cone job. I will say that ALL of my rifles are coned an I've never had a single problem out of them. There good shooters or they would be finding a new home. I do the cone jobs myself an follow the instructions to a tee. Sorry your having trouble but before you cut that barrel I would keep at it for just a little while cause you just might find that just right load :thumbsup:

 

[Bill Hall]

There are a few other factors, in general, that will affect accuracy like what you're describing. Loose barrel, sloppy barrel bedding, loose sights, sloppy breech inletting, loose tang screws, anything that can cause a wiggle in the barrel or sights. You might want to check out those potential causes before you start on the crown.

Also, I don't know much about coned muzzles, but I wonder if you could just touch up the cone, instead of cutting it back. In other words, have a qualified machinist or other knowledgeable person just true up the cone. Might not remove very much metal, and you wouldn't need to re-do the whole muzzle area of your rifle. Maybe someone can chime in here for an answer. Bill

 

[ericb]

How deep does the Cone go? If not very, I s'pose you could somehow refresh/redo the cone properly - hate to see anybody whack off Barrel unless they really need or want to.

Eric

 

[detent]

Crowning a barrel can certainly make life a lot easier fore muzzle loading and helps protect muzzle damage to most guns but if its not done properly then its a very quick way of ruining a good barrel. If you cant do it correctly in a lathe using the bore as a reference point then best to leave it flat, the barrel must also be in parellisum to the headstock bore.If you have it recut by a good machinist then it should be ok as long as its not to deep already Basically bad crowning tips the projectile over to one side on exit from barrel this generally effects bullets more than it does ball. When we build 1000 yarder's we clock the bore into one tenth of a thou.

 

[Fred_Dwyer]

A couple questions yet; is this a new, never shot before gun and maybe needs shot-in or lapped... or new to you used gun that is shot out?

 

[SR James]

Sights, tang and other screws, and other such things were checked for looseness at the range. Loose sights was one of the first things I thought of. Everything is tight. I pulled the barrel when I got home. Inletting is good, snug and even. The breech area of the stock is glass bedded and contact with the breech end of the barrel is excellent. Regardless of how one may feel about glass bedding a longrifle, the fit is very good. Barrel pins are not excessively tight. The barrel stayed cool throughout the shooting. I can't find any mechanical gremlins with the exception of the coning. It appears to be even but as I said, this is my first coned barrel. I'll try to take and post pics tomorrow. This is otherwise a nice rifle and I'd love to get it to shoot. Maybe the collective minds of the forum and figure it out. I appreciate the suggestions so far.

 

[Bill Hall]

It sounds like it's taken this long for us to get up to speed with what you've already logically eliminated :surrender: . It's obvious that you're no slouch, and I think any experienced shooter would follow your same process of elimination, and probably come to the same conclusion.

I think that GM barrel is a 1/48 twist, Yes? If so, you got the correct rifling for a .40 cal round ball. That eliminates bad rifling , unless something screwy is going on in there. You might shine a light down there just to make sure the rifling is good. You say your fired patches look good, and loading feels normal. And all those other things I mentioned are normal, so....Looks like the only thing left to accuse would be the coned muzzle.

I just can't think of any way to trouble shoot the suspected bad cone without either cutting it back, like you mentioned, or re-doing it, if that's a real option.

If it's a fullstock (and I'm sure it is), I assume you're going to need to re-do the front of the stock if you cut the muzzle back. Not a big deal if you have the skill. I still wonder if just touching up the crown is an option though.

Well, those are my ideas. Good luck, tell us how it works out. Bill

 

[MikeC]

I've coned three barrels using Joe Woods tools. One of the rifles accuracy clearly was improved, the other two no change, just easier to load. I'll never own another muzzle-loading rifle without a coned barrel. If the proper tool was used I don't see how it can be the coning from my experiences.

 

[aeatwood]

I just use the ball of my thumb and 400 grit emory paper to break the sharp edges. Takes about 5 minutes and if you keep turning the barrel every 30 seconds or so, you will do it evenly and not affect accuracy. Makes it a LOT easier to load tight combinations, and they don't cut the patchs.

 

[Robby]

Alan, That would be crowning as opposed to coning, which goes deeper into the bore. Personally, I don't see any advantage to loading with a coned barrel. Like I said, its a manure shoot as to how it will affect accuracy. I would always advise against it.
Robby

 

[Rifleman1776]

I'm now with the others on this.
It seems like you have eliminated most of the usual variables.
My long-distance guesstimate now is (also) that the muzzle is not square and/or the rifling at the muzzle is, somehow, messed up.
These frustrations are what keep us in this insane ml game.
Ask me about my fowler....... :shocked2: Nebber, mind. Don't. :td:

 

[SR James]

Ok, guys, here's a couple of pics. The first one shows the coning. Sorry I couldn't seem to get a shot of the entire muzzle. But it appears to be pretty even all way around. The bright spots on the crown are not nicks.

This shot shows the muzzle end of the rifle so you can get an idea of what would have to be modified if I do shorten the barrel. Which by the way, I've sucessfully done on a couple of rifles I built during the barrel shortage when all I could get were barrels longer than I wanted. So I have the ability to shorten if needed.
So suggest away. I'm going to try to do a bore casting of the muzzle to see if I can figure out how long the coning taper is.