Well, I took my GPR to the range today and replaced the stock nipple that came on my .50 with a TOW replacement nipple that fit well and didn't wiggle in the threads and voila ... I cleaned it afterward and the nipple easily came right out. So, I'm thinking that the thread tolerances on the stock nipple that came with the GPR are the problem. The stock nipple on my GPR is simply a bit too loose and no amount of gorilla grease or nipple anti-seize is going to help. I'll use Teflon tape next time on the stock GPR nipple and see if that helps. I also noticed almost no fouling around the TOW replacement nipple, and I had a whole lot of BP residue using the stock nipple.
