I don't know about the "dealers" but every "decent" shop I know uses the long needle adapter mentioned by Ken. I've got a picture of one in my photos if you want to compare the various grease gun tips. I ground my "normal small fitting" nose down to .480 and it works fine on most hard to get at zerks. It worked fine on the front Tundra fittings until I put the transmission skid plate on and now I use the long needle adapter, as it's a lot easier to reach the zerk with the extended body on the adapter. When I ground my fitting down, I did so by trial and error to make it fit the tight spots on my old 4X4 and had no idea of the actual diameter until now as I just measured it for you as a go by.