Umarex's S&W 586 CO2 replica is well reviewed, and would give you a similar sight picture to your M14 -
http://www.pyramydair.com/cgi-bin/sh...26%20%20Wesson
I'd never gotten comfortable w/ my Daisy 747. The grips tend to fatigue my hand. So I use a FWB 103 and Steyr LP 50. But these probably cost more than you'd want to spend for a first air pistol.
The Drulov DU-10 is another option. This is a CO2 semi that's set-up much like an ISSF standard pistol.