Weaver "Guide series Quad Top" sold by Gander Mountain:
"med" too low for 50mm on fluted Ultra, actualy contacts
the barrel.
"high" clears barrel by just over 1/8", slight adjustment
ring issue depending on were scope is placed (eye relief).
Minor to minimal grinding for 100% clearing the adjustment
ring.
The Guide series apears very solid for aluminum, quad top
anchors very solid, cheap at $14 and well worth it from
what I see on my bench (next to high dollar rings).
Im gonna give them a two thumbs up, cheap and solid.
*This is on stock H&R long (discontinued) ultra base, my
"new" gun was built in 06....it's 11/08 now!