The 6.5x20 Leupold is a staple amoung veteran silhouette shooters. Today there are tons of scope options with a new manufacturer every day it seems. Nobody knows optics and their practical application quite like silhouette competitors. The herd of scope choices gets narrowed down to just a few for long term use on competitove rifles.
These include:
Leupold- 6.5x20 LER
Leupold- 6x18 VXII ( I have one and love it )
Leupold- Silhouette 25X or 30X
Weaver T-24 ( I have one and love it )
Weaver T-36
Bushnell Elite 4200
Burris 4-12X32 air rifle ( I include this because of my personal experience with it. It is just the right size for a hunting rifle with great optical quality in low to mid range power. It is perfect for a dual use hunter/comp rig with all the features that silhouette shooters demand. Burris scopes are made in the USA. It has served me well on silhouette small bores, and has stood up to 15 years on a Beeman RX gas ram without a single problem. There is no greater test for a scopes dependabilty than that. )
For rings I love the Burris Signature Zee for their adjustabilty in any direction, and elimination of any missaligment.