I believe the lead slugs are for finding and measuring a tight spot. I also believe to do a good lap you have to cast your lap in the barrel. This is what the barrel makers do.
Pour a lead lap on you cleaning jag and stroke the barrel with some grease. You will get a good feeling of the barrels uniformity
A guy that worked for Bill Wiseman once told me that shop used 280 grit to lap new barrels.
Lap it too fine and it will copper. 320 is tops.
Yep, that is probably right...I honestly didn't really see any difference, in appearance at least, from the 220 to the 600 in my borescope. Maybe if I had a really good barrel that didn't need it anyway I might be able to see, but then, if it don't need lapped anyway I wouldn't be messing with it. Yesterday evening I shot a .527" group with this little rifle....I like to think it isn't all the glass bedding. Not hardly fouling copper at all.
Now I have to do the magazine mod so I can seat the bullet closer to the lands.
Sounds like you did a great job. Congrats. Any pics of the process? Inquiring minds are very interested.Curious how the lap is poured.
Regards, Paul
www.boltfluting.com