FYI, Sinclair has a one piece Leupold Long Range Base that adds 20 MOA and uses standard rings for $19.95. Part #L51732 Rem Long Action, and #L51734 Rem Short Acction. They have also began carring Ken Farrell Long-Range Bases in one and two piece. They will add 20MOA. More Farrell products are offered on their website: www.kenfarrell.com.
They are very high quality products priced under $50. Shipping is free too. I installed two of their one piece bases on a Rem 700 and a 98 Mauser, perfect fit. Will order from them again.