I haven't done it.
My feeling is that it will accelerate erosion in the forcing cone area. There is also a danger of the abrasive imbedding in the bore. I don't think it will hurt the gun that much if it's shot out, has a rough bore, or is difficult to clean. When I put together a sporter rifle in .358, I ran a jag with a patch soalked with lapping compound through the bore several times. After Cleaning it and repeating the process a few times, I noticed that it was considerably easier to get the patch through the barrel. Once chambered and cut to length, I treated the bore with Tetra-Oil per their instructions. You'd think the barrel was made of Teflon. Nothing sticks to it. The rifling still looks sharp. The barrel did look like a mirror at first but has dulled a bit. Accuracy is superb.
Three advantages to fire-lapping IMHO:
1- Easier cleaning.
2- More consistant accuracy and velocity.
3- It's easy.
Again, like other's have said, if your gun shoots fine without it and isn't a bear to clean, don't mess with it.