Well here I am trying different calculators and options for rings but none of them seem to make perfect sense. Too subjective.

I basically have a R700 footprint. 20 MOA base. Shilen #5 light varmint contour.

Need 34mm rings. Scope objective OD is 2.6", plus 4-6mm for lens caps. So say 70-72mm OD total.

Do you think 1.125" rings would work. Or 1.375" at least?

I am guestimating your objective OD @73.7mm when you include covers (2.6 + 0.25 = 2.85 which I rounded to 2.9"...  2.9 x 25.4 = 73.7...)  say 74 mm for round numbers.  So for your objective bell to be even with the top of the rail, the ring height would have to be 1/2 of 74 mm = 34 mm or 1.34".  The bottom of the rail is about 3 mm lower so for the bell to be even with the top of the action (bottom of the rail), you would need 31 mm or 1.22".  How many mm below the level of the top of the action is the top of the barrel at the point where the objective bell will be???  A straight edge across the top of the action extending toward the muzzle will help you estimate this...  

Rob, you obviously have a 20 MOA base as well?  Didn't think I could go lower than 1.125". My scope (Cronus) has almost identical dimensions as the Razor 4.5-27x56.

I put a straight edge on my 20 MOA base till it extended past the shank of my barrel and the contour started. At that point (where scope bell would position) it measured 1/2" (12.7mm) between top of base and barrel.

My last precision rifle I setup was when I lived near a LGS that had every size ring option in stock. I've since moved and don't have that luxury now. Going to have to order online. Seekins, Badger, or NF.

20 points to the winner who helps pick the correct height

34 mm - 12 mm = 22 mm (minimum) to clear the barrel.  1 inch = 25.4 mm so @ 1" you should be good to go from a clearance point of view.  What you find "comfortable" might be another matter...  

Free advice (worth what you paid for it?!?!) on ring recommendation - Leupold Mark 4 rings - High = 1.1"...  I like the steel version (link) but they are also available in aluminum.  They're solidly built, reasonably priced ($142) and don't require loctite on the screws in the ring tops (according to Leupold).  Also available in "Super High" @ 1.4".

Good luck!  Post pics & "the story" when you complete the build!  

I found a better calculator and it confirms what y'all have said pretty much. looks like I'm going with 1.1" or 1.125". Was looking at either Nightforce 1.125 or Leupold MK4 1.1".

I've got an XLR chassis, so adjustability is not an issue.

I like the chassis but I sometimes miss an A3 or A5 stock.

So I went with 1.125" rings and I've got 3/8" (0.375") clearance between the objective and barrel. My Vortex caps aren't in yet so I can't measure with them. I'm wondering now if I should have gone with 1.00" rings? I almost feel like the scope isn't low enough. I've got plenty of adjustability on the chassis, so cheek/head placement isn't an issue. Just visually looks like more of a gap than I had on my previous rifle

What do you think, leave em or return for 1.00" and be Very close with Defender caps on?

All that effort for 0.125" or about 3 mm?!?!?!?  I wouldn't...