That's interesting. I haven't seen that with any of my guns after using Frog Lube. I have few rifles I don't handle very often, used Frog on them and don't have any build up. Did you use just the paste? If so, where? I use the paste for only certain areas and I wipe away excess as suggested. When I am done, there is a nice coating where I've used it, but not over the top build up or excess.

As someone mentioned, Frog Lube (best price is in the kits), is spending, but it goes a extremely long way. I use on all my guns, never a problem and use less than I have with other cleaners and oils. And I am meticulous when cleaning my guns either after shooting. If I know it's going to be awhile before I use one of my guns (normally rifles), I clean them, store them and pull them out to check and clean again in a few months.

Maybe you left to much paste in your gun? I don't know, but I never had a problem.