restoring a buggared up muzzle?

[Black Jaque Janaviac]

I won't bore you with the long story but does this muzzle look like it could be the cause of some accuracy problems?  The gun used to cloverleaf them at 50 yards, now its about 2.5 inch groups.  The crown has been given a smooth radius and the grooves deepened some to facilitate starting a ball. 

Could I just buy a round grinding ball from McMaster Carr and grind the crown back to a crisp edge?  Would that help restore accuracy?

[Scota4570]

I'd properly crown it in a lathe.  IF it were mine I'd shorten it a little and move the nose cap back.  That way you know you are back into undamaged bore. 

At least use something with a pilot.   Just removing material with no way to keep it centered is likely to go badly. 

[rich pierce]

I agree that the best course of action would be to cut an eighth of an inch off and re-crown. I recently took about that much off an original barrel. I had freshed the rifling but was trying to avoid altering the muzzle if possible. Sometimes it has to be done and was routine back in the day.

[P.Bigham]

Hard to tell but from the photo it looks like there is a sharp edge where the crown meets the lands. Could be cutting the patches.   Could be a lot of things causing loss of accuracy.

[Black Jaque Janaviac]

It's not cutting patches.  I recovered some and they look like you could re-use them.

So how does one go about moving the nose cap back? This one is epoxied and pinned to the stock.  That's really what has got me stymied.  I've restored or fixed bad muzzle crowns when the barrel had enough protruding that I could file back until the crown was gone and then start over.   

[BOB HILL]

Just wondering , would this be a candidate for coming?
Bob

[Frank]

Just wondering , would this be a candidate for coming?
Bob

I was thinking the same thing. Joe Woods tool should correct the problem.

[Hungry Horse]

 I’d try the round stone bur first, and if it didn’t work you can alway go with the guys that perpetually choose the hardest most expensive remedy. I’ve used a stone bur followed by some fine emery cloth on several barrels with good results. You have to buy a good quality stone, a little bigger than the bore, but not bigger than the crown. You have to do some rotating of the drill motor to insure and irregularity in the stone doesn’t cut a groove.
 I suspect your problem stems from when you filed the ends of the grooves. So any grinding with the stone will have to go deep enough to remove that. Good Luck.

  Hungry Horse

[FDR]

Heat will break the epoxy bond. I would use an electric heat gun to supply the heat. Try Harbor Freight for the heat gun.

Fred

[Scota4570]

Heat will work.  I would use a small propane torch, a heat gun will  take longer and increase the chance of buring the stock, at least in my hands.

[Robby]

I agree with Hungry Horse, try the simplest solution first. Never pull the engine when you just run out of gas.
Robby
Oh, and when its running like a top, never say to your buddy, hold my beer.
R

[B.Habermehl]

I would use Hungry Horses method first or one of the stones with a 45 degree point. Slow with a light hand with a eggbeater drill. Then emery paper as described by Taylor S many times on this forum to deburr. Just go deep enough to clean up the existing crown modifications. Use a magnifying glass and good light to be sure you’ve cleaned up the existing work. I bet a hours hand work will fix the problem, as long as you are careful. BJH

[Daryl]

It all sounds good to me, except for coning. That being, if you want to get back to cloverleafs at 50yards.
I would use a 45 degree stone in a drill, then emery or wet/dry paper to smooth and polish. The crown will
just be a bit deeper, is all.
I suspect the filing is what is disturbing the accuracy.

[Scota4570]

Anything you do that follows the existing will likely not help. The messed up part needs to be removed.  The new crown needs to be accurate. 

[Top Jaw]

The Dixon book recommends using the ball shaped cutter, and rotating the drill in a slight circle as you go, (as has been said), to avoid any irregularities in the head surface. 

[Black Jaque Janaviac]

Thanks guys!  I will probably go the route of grinding with a ball.  Although, after some more shooting I am not sure this is my problem.  Last time out she seemed to group the balls tightly - just several inches higher than usual.  I had this problem before and thought I corrected it by lengthening the slots on the barrel staples. 

Does tightness of the lock screws have an affect on accuracy?  If so how do you manage consistency?

[Daryl]

Perhaps, but likley not.

[Rifleman1776]

As deep as that is a ball might not clean it up enough for you. I suggest a 60 degree cutter held by hand. But, first do check out all other possibilities for the bad grouping.

[jerrywh]

If you crown a barrel with anything but a lathe you really need a tool that has a pilot in the bore. Round stones and other similar tools are not a sure way to get a concentric crown. Tools that do not have a pilot will often work but sometimes they won't. Tools with a pilot always work in the hands of a knowledgeable gunsmith.  Let the argument begin.

[Not English]

Jacques, Like Scott says heat works. I'd pull the barrel and drill out the rivets first, then heat it with a propane torch. Keep it moving and avoid burning the stock. When you see the metal starting to sweat slightly (moisture bubbles), then it's time to  try and remove the cap. If it doesn't work, a little more heat will help. It will come off.