Remington did make a .22 caliber Pioneer rifle. There are very few references to it so it must be a low number production item and obscure. That does not make it any more valuable , first there must be a demand for it. The 750 Pioneer and 765 Pioneer are listed in the " Rifles of the World " by John Walter. In production 1948 until 1954. The 766? well there is no reason that Remington couldn't make a minor change to the 765, such as different sights and Voila, the 766, common practice.