Turbozag:
I’ve never used Tetra, so I’m certainly not disagreeing with you.
However, your statement that it increases velocity by 100 fps or so is, in my view, not necessarily good. Rifle accuracy is dependant upon consistency. Seems to me that as the Tetra in a rifle bore is worn or burnt off, it will cause the bullet velocity to change.
(Ironically, in some situations lubricant in the bore can apparently cause a reduction in velocity instead – but that’s a different issue.)
Anyway, when I’m really concerned with accuracy, I use a thin coat of regular (cheap) gun oil in the bore strictly as a rust preventative. (I use FP-10 everywhere else.)
I patch this oil out of the bore before shooting the rifle, in part, to avoid velocity changes. I’m afraid modern, really high quality oils are going to be too tenacious to remove easily.
Admittedly, I’ve never done any testing to confirm my concerns.
Just something to think about. YMMV