There must be many variances on lapping. A friend of mine used to work for a custom rifle builder. What they called their lapping was done to the barrel blanks before any machining was done. There lapping was ultra fine steel wool on a wooden dowel ran back and forth through the barrel. This is a very well known rifle builder with very accurate rifles. This whole lapping thing intrigues me. So many different points of view. Is there a solid way to compare all the different methids? By no means do i think it hurts but is it needed and to what extent. Ive seen numerous $225 savage rifles shoot .5moa. I doubt there is any lapping done to them. So is it needed? Im not sure. Ive been told before that the machining on a barrel determines its accuracy. Lapping and break in mainly let it achieve its accuracy potential sooner. I dont have a clue. Only things i have seen and been told. Love to see where this thread goes. Always ready to learn.
Adam
There are many different ways that this process is done and just as many different results based on what the builder/barrel maker wants.
Knowing what the lapping process can/does do I truly believe that lapping should be done to a barrel blank so the smith can remove the belled out ends. (When a lap is reversed, it removes more metal because the compound shifts and cuts more material in the first 1/2 inch or so). Lapping after a chamber is a process used to smooth out the machine marks from chambering and it is very hard to start the lap correctly so they use steel wool or something else that doesn't need to start in the rifling. I consider this more of a polishing than a true lapping because it doesn't get to the bottom of the groves like a cast lap does.
Reversing the lap at the end of the stroke(Before exiting the bore) has the same effect as reversing a Bronze brush in the bore while cleaning. First it doesn't want to change directions and when it does it can leave marks. Lapping compound can do the came thing but in the process it removes more material than normal because it is harder than the barrel.
By lapping the barrel before cutting the chamber you eliminate the belling effect in the bore when you remove this part by cutting 3/4 " off the muzzle and chambering the breach end allows the reamer to remove this on the chamber end.
To accomplish both lapping and removing machine/reamer marks I prefer to break in the barrel and remove any defects left by the barreling process and smooth out and chambering marks left by the reamer in the throat lead and Lands left by the pilot.
Combining different task doesn't always give the best total results so I believe in solving one problem at a time so each is as good as possible.
Most everything we do to get accuracy requires attention to details and short cuts are just not in some peoples vocabulary/processes. All things are not created equal and sometimes require adjusting to the plan to get the best outcome. Machines can be very repeatable but craftsmanship can be flexible when needed to produce fine quality.
Just my opinion
J E CUSTOM
