Crowning/Lapping a muzzle

[Pb2au]

I had been getting some very strange fliers on my M92 Rossi as I monkeyed around with load development. The rifle will pattern generally well, with the occasional strange flier blowing up the average.
Last night I put the patient on the workbench and went over everything with a fine tooth comb. What I discovered were two nicks/burrs right on the transition from the muzzle face to the bore. There are in the 11:00 and 5:00 position. They are very small nicks, but significant enough to catch the fibers of a Q-tip as I pulled it from inside the bore to the muzzle. So in my mind, this most likely could be my culprit.
Now what to do.
I'm keen to get some feedback as to when lapping is not enough and re-cutting the crown becomes necessary.
Many thanks in advance.

[OuchHot!]

I cannot really assess whether this is the cause of your fliers...I've seen bad crowns do this but it kinda depends on your definition of "occasional". Assuming that you have found the problem, is the damage shallow enough that you can lap with a ball headed brass screw and grinding compound? This is sort of the least invasive but it only touches the transition. If you have deeper damage then a purpose made cutter (with pilot) is a good idea. The brass ball headed screw chucked in a drill is easy, quick and usually wont make things worse.

[Pb2au]

Again, it seems likely that the burrs could be the culprit, as everything else seems in order. But as they say, every gun is unique.
I plan on using the brass screw head plan and lapping them out. I reckon if a reasonable about of lapping doesn't remove them, then I will give our friends at Brownell's a ring and get some tools on the way.
I am hoping this will also explain the reason this rifle has shot a bit to the right consistently. I was able to drift the front sight over and bring it on target, but it has always bugged me the amount I had to drift it. Just more than I would normally expect. Sometimes you just have to go with your gut feelings and try...
We will see Sunday when I head to the range.

[johnson1942]

if it constantly shoots off in one direction no matter what you do with the sights, its the crown. an easy fix to be made better than new.

[OuchHot!]

This might be internet myth, but I understood that a low end imported double rifle is being "regulated" by grinding one side of the crown (rather than by adjusting wedges between the tubes). I certainly hope that isn't true but it does sound like crown damage can throw a bullet systematically off. I have had to do the brass screw/fine compound treatment to several air rifles....they are real sensitive to crown problems. I've got a few piloted cutting tools for bigger jobs on revolvers and they have worked well.

[country gent]

I have used the brass ball and lapping compound for years to touch up crowns at times. A brass ball ( or brass round head screw) on a stem and various grades of lapping polishing compounds will keep crowns in great condition. I do this by hand using a back and forth rotation in a figure 8 pattern and light pressure. Insert a patch into muzzle leaving only the room needed to work ( this keeps grit out of bore). Lightly coat ball with somewhat coarse grit and work slowly rotating the ball back and forth while moving stem in a figure 8 pattern this is the longest amount of time polish out dings scratches and any other damage. Vlean bore and muzzle replacing patch in the bore with clean one. Coat ball ( same ball cleaned) with finer grit and slowlu lightly work to polish crown. when all is even marks and looks good clean and remove patch from bore. You can stop here or go to a very fine polishing compound to get a nice bright finish in the same way as above. I have used a patch wrapped around the ball in this step and rouges to bring out a bright polished crown.
This techniuqe has been being used for years and is easy to do. The ball naturally follows the bore and makes for a burr free crown quick and easy