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Posted: 8/9/2010 4:10:37 PM EDT
| Has anyone done this? Is there anything special to know about the process. I dont have any big dings at the muzzle but I just want to sharpen up the crown, to see if it brings the accuracy back up. |
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Quoted:
Has anyone done this? Is there anything special to know about the process. I dont have any big dings at the muzzle but I just want to sharpen up the crown, to see if it brings the accuracy back up. I would not lap the crown area. This is where the accuracy of the firearms is. Do not do anything that could effect the seal and fit of the round at the muzzle or you will be sorry. If you are going to do anything re-crown it. |
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With a sharp cutter I don't get burrs. I feed in .035" in increments of .010", and then .005", pulling out each time 1/3 the diameter of the muzzle, till the last cut, at which time I immediately begin pulling out on the compound to generate a nice angle.  That's what it ends up looking like. That's an AR barrel I re-crowned. |
| 11 degrees? Very nice cutting. Do you have issues running inserted cutters? We normally run carbide or inserts on the lathe but I can come up with some hss if need be. Did you cut those threads? If so, great job! Eta: What is that gold back at the jaws, is that a chip or something else? |
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I leave my compound set at 29.5 degrees, so that's what the angle is. The crown proper is 90º to the bore. HSS is preferred, particularly if you can come up with some Crucible bits. I can't remember the number off hand. I can look tomorrow. I haven't run across any insertables that are sharp enough to make a good crowning tool. They all leave burrs. ETA: The gold is some brass shim stock so I don't mar the barrel unnecessarily. A mark you don't put in is one you don't have to polish out. |
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I also feel like I need to point out that I use power feed when I'm pulling out on the crowning cut, just as slow as the machine can possible feed and the highest spindle speed it will smoothly run. This produces a smoother more consistent surface than trying to just do it by hand. The angle is fed out by hand, but real slow and smooth. |
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Here are few I have done...two for AR's one in 5.56 and one in 6.8rem
the bottom one is on a .308 mauser re-barrel 11degree done on a lathe like described above and polished by hand very carefully with 2000grit paper on a hard backed mount.... 
bad photography is all mine 
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