Got a flattop AR carbine with a full front sight base.  Thinking about using a scope with 42mm objective lens. Which ARMS #22 height should I use?
-Update-
Thanks again, folks. Got the scope mounted with ARMS #22 high and was able to get it dialed in today. Shot around 1 MOA with Q3131A and sub MOA with Winchester 40gr ballistic silvertip as well as Remington 50gr v-max all at 100 yards. Interesting thing was the trajectory of all three ammo types were within half inch of each other. Love the ARMS and removable carrying handle setup. No noticable zeroing deviations after swapping them around.

#22High rings will place the scope at the correct height for a proper cheek weld.

Edit: They're great rings; you'll love 'em.

What he said. I usually lean toward compact scopes, so I tend to forget the length issue. Thanks, PaulE, for taking up my slack!

i thought the motto was fortune favors the BOLD?

Hell, maybe it does. And it matters how?

Thank you, Zardoz and PaulE. Once I get the scope mounted on my AR, I'll be able to put the 10/22 away and go after those groundhogs at a much farther distance.

Glad you like the rings! At 100yds, you won't see much of a difference in trajectory, but way on out there, it'll be obvious as hell. You really need to zero the scope with the same type of ammo that you'll be using for hunting.