I think nothing has been mentioned on this forum about sizing or lubing lap bullets because those questions are made clear in the instructions I send with the LBT lap kit, so it didn't seem important to repeat it here.
Don't size unless you have to, to get the lap compound charged bullets to chamber, and don't apply LBT lubricant in the grooves. In fact if you apply any one of the LBT lubes it will stop the compound from cutting! That's a bragging attribute about LBT lube. No other lube I know of will make any difference. Maybe this is worth thinking about if you ever carry your gun where wind blows dust around, which is everywhere when it isn't raining!
Application of LBT bore lap compound increases diameter by about .002 thousandths, which may dictate sizing on tight chambered guns. LBT bore lap was especially developed using my personal experiance and testing, and from feed back from thousands of barrels lapped. It is a very specially developed mix of grits, in a special carrier (cutting grease), to make it cut the lumps out of a barrel fast as possible, without cutting scratches, while removing minimal amount of throat.
If you are using any other compound, you are on your own, and my instructions may or may not apply. I've heard of many who took out 3 to 4 inches of throat, lapping with other compounds. They saved the price of an LBT lap kit though, minus what they spent for whatever ruined their barrels!
I hate to sound like a hard headed pusher of my own products, yet I have to when I'm dead sure I have the best, and especially on lapping. Bear in mind that I developed the fire lapping process about 25 years ago and have counceled thousands of customers on it. You are buying my experiance when you use the LBT lap kit and follow my instructions ONLY, and when you do, you will not be dissapointed with the results. I've not heard of one person who has been in all these years. In this same vein, I really don't like it when people go with other peoples ideas then call and ask be for advise or solutions. But I'll gladly take as much time on the phone as anyone needs if they are using an LBT kit and trying to follow my instructions, but run into any kind of snag.