Very Leaky Valves

Ok. So I finished installing a number of valves for my shower remodel project, feeling pretty proud of myself until I turned on the water. The 4 NPT joints on two specific valves (but none of the others) started leaking alot right away. I'm not talking drips, here, but rather a solid stream. I tried tightening them, but they were as tight as they'd go. Looking at the installation a bit more, I noticed that the fittings were pretty deeply set in the valve bodies, so much so that I started thinking that they maybe had bottomed out, preventing adequate tightening and proper sealing at the threads (I'm using teflon paste instead of teflon tape). Could it be that the fittings diameters are a bit too small, or that the valves thread diameter is machined a bit too big?

So, I took off one of the 4 leaky NPT fittings, compared it to a bunch of others I had, and managed to find one that seemed a hair larger. I installed it, and sure enough, no more leaks. In fact, looking closely at it, this new fitting did stand out a bit more (looks like almost 1/16"...) from the valve body than the other 3 leaky ones. So, I guess that my assumption was correct.

Any suggestions for fixing this? Could I go through the bin of fittings at the Home Depot to find the biggest ones possible (aren't sloppy manufacturing tolerances great...), or rather use teflon tape and build some diameter on the fittings I already am using. Interestingly, the valve distributor suggested that I use some "pink" teflon tape. Pink? Never saw this. Maybe it is just a thicker version of the white one we all have.

Does any of this make any sense? Thanks for any help or suggestions. Phil

Take those valves back, allow them to notify the mfg of the problem so they can destroy those valves if they are incorrect.

I haven't seen problems with male adapters as long as the heat is kept down.
I solder the fittings on the pipe first, dope them, and tighten them up.