Here's the deal:
I'm scoping a 20" AR-15A4 with a Leatherwood M600.  In case of scope damage/malfunctions in the field, or just because, I'd like to be able to switch from the scope to a removeable carry handle quickly with no tools.  Since the scope needs to be raised about a half inch anyway, I was thinking about mounting it on a pair of ARMS #17DRs.  Throw the levers, yank the scope, and slide on the carry handle.  Anybody have any experience using these mounts for something like this?  Do they really hold zero as advertised?

Arms Rings and bases are very good and for years were the standard. However there are new and better systems out there. If I were setting up a 20" like you are I would go with a GGG Rail to raise it to the height you want. Then I would install a GGG MADD BUIS. These lock and have a precision retical in them that is suitable for most applications. I would then Mount the Scope in a LaRue SPR or SPR-EE  scope mount depending on required Eyen relief for tha scope.
If yo are set on using the Carry handle as a BUIS system, I would consider LaRue Rings, I believe, and someone correct me if Im wrong, they make a High set that wold fill your needs well.

As for the ARMS holding Zero, my experiance is they will for a while, but over time they get sloppy.

cp

CP, thanks for the info.  I already have the carry handle and the scope, so I'm committed on both counts.  Plus the length of the scope precludes the use of a flip-up BUIS anyway.  The Leatherwood does not use rings as it has an integral mount that fits a M1913 rail.  So if I want QD ability, it has to be a riser of some sort.  Is there a better riser alternative than the ARMS for this?  I already have a set of risers but they tighten down using machine screws, which means questionable zero when R&R'ed, plus I'd have to carry an allen wrench in the buttstock.