aterry33
Member
Can someone please describe this process and the purpose for doing it on a revolver?
Lapping the forcing cone
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BruceM
Member
Prevent leading and other bullet deformation issues. A more common alteration is re-cutting the forcing cone to a shallower angle which, once again, helps resolve some of the same issues.
Bruce
Bruce
john traveler
Member
Lapping is a process of imbedding an abrasive in a soft material (the "lap) and using it to polish a harder surface. This is usually done with a shaped-to-fit lap, as in a cast lead lap in a gun barrel to fit the land and grooves exactly. In the case of the lapped forcing cone that you asked about, the lap is a brass, aluminum, or lead cone that takes on the dimensions of the lapped area. It is coated with fine abrasive or polishing powder and oil, and spun in an electric drill motor or with a drill press, or lathe.
The so-called "fire lapping" method of firing abrasive-charged slugs through a gun barrel is intended to be a quick method of smoothing a rough bore or forcing cone. What it usually does is ruin the barrel for any hope of serious accuracy.
The so-called "fire lapping" method of firing abrasive-charged slugs through a gun barrel is intended to be a quick method of smoothing a rough bore or forcing cone. What it usually does is ruin the barrel for any hope of serious accuracy.
dfariswheel
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Cone lapping is normally done as the final step when cutting or re-cutting the forcing cone.
This smooths off any roughness or marks left by the cone cutting tool.
This uses a brass tapered cone lap of the appropriate angle, available from Brownell's, and lapping compound. You must use the right brass lap for the cone.
This is done with a "Tee" handled rod that fits down the bore. The lap is coated with compound, the lapping head is pulled into the cone with the handle, and the handle is rotated to lap the cone.
Since this is almost always done with the barrel on the frame, it isn't done with any power tools, just by rotating the handle by hand.
This smooths off any roughness or marks left by the cone cutting tool.
This uses a brass tapered cone lap of the appropriate angle, available from Brownell's, and lapping compound. You must use the right brass lap for the cone.
This is done with a "Tee" handled rod that fits down the bore. The lap is coated with compound, the lapping head is pulled into the cone with the handle, and the handle is rotated to lap the cone.
Since this is almost always done with the barrel on the frame, it isn't done with any power tools, just by rotating the handle by hand.
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