How to know when crown needs touch up

[tenring]

Is there any way to visually determine when a muzzle crown needs to be re-faced?

Is pulling a Q tip thru the bore sufficient to find burrs?

Can a garden variety tinkerer use this tool to lap a crown?


.brownells.com/gunsmith-tools-supplies/barrel-tools/muzzle-lapping-tools/45-brass-muzzle-lap-prod679.aspx

 

[GenePoole]

I've found that tool to be pretty useless. The pilotted PTG tool is better, but I find single-point crowning on the lathe to give the best results. As to when it needs done? That's a mystery. I had a tactical rifle that started to open up at about 800 rounds. I checked everything, but couldn't find anything out of whack. A fellow shooter asked me what barrel I was running. I said Bartlein. He said recrown and it'll be fine. I could find nothing visibly wrong with the crown, but I gave it a go anyway. I whacked off about 0.250 from the end of the barrel and single-pointed a fresh 11° crown and it shot fine after that. I don't have any idea how or why the guy thought there was something peculiar about Bartlein and no one else has offered up any explanation, but it worked.

 

[watercam]

While single point cutting IS the best, I have used the piloted 11º (or 79º depending on how you look at it) Brownells cutter very handy for 'touch-up' crown repair. Followed by a VERY slight 45º cut with piloted cutter. Then lap if needed.
I use a magnifying glass or my bore scope to inspect the crown - with enough magnifying power one can see the rounding of the edges pretty easily.
But then I am a cheap B_____d.