My new G mount and K16i arrived, and were installed tonight.
The combo works perfectly.
I de-greased every bearing surface with acetone, including blowing out the blind-holes in the mount, and de-greasing the screw-threads. A slurry of aluminum chips was visible from the blind-holes, and the screw threads showed similar, as well as grease and what appeared to be a brown rust-preventative. This is typical for this type of product, and not exclusive to Geissele.
Rag from cleaning screws:
Once all surfaces were clean, the optic was leveled with a plumb line and Badger Dead Level, and the front ring-cap finger-tightened to stay the optic.
Accomplishing this, a small amount of Loctite 222MS was added to each blind-hole of the rear ring-cap screw blind-holes. Loctite 222MS has a k-factor of 1.15, or roughly identical to "light machine oil".
At this point, the rear ring cap was lowered into place, and the screws hand-threaded until snug, and the gaps on either side of the rear ring-cap feeler-gauged equal. They came in at around 13 thousandths of an inch, respectively.
A Vortex torque wrench set to 16 lb-in was then use to torque the screws into place incrementally, using roughly 1/6th of a turn per screw, until the wrench indicated final torque was achieved. I find that angular torquing until final measure, results in more even clamping force.
The end result was a 0.004" gap on the right side of the ring-half, and a 0.004" gap on the left. Here is the tightest juncture, and a 0.003" gauge easily slides into place, a 0.004" with the slightest of persuasion. On my last G/K16i combo, at 16 lb-in, I was barely able to slide a 0.0025" gauge in one side, and the other side was clamped solid. Using a k-factor of 1.15x16, arrives at 18.4 lb-in. The maximum torque geissele recommends is 18 lb-in, and they recommend installing the screws with the light machine-oil that is present on them from the factory, which should have identical k-factor to 222MS. The tightest torque that Kahles recommends be used with their K16i optic, is 240 Newton cm. This equates to 21.24 lb-in. All torque values used fall within industry standards, and recommended values from both the optic and mount manufacturer, in this case.
A similar process was followed with the front, with similar results, although larger gaps were appreciated, ultimately, being 0.007" on the right, and 0.006" on the left. I would also note that using a micrometer to measure bore ID's static with the rings fully clamped, as they arrive, the rear ring ID measured 1.164", and the front 0.002" less, as best I could tell. A caliper is NOT the best tool for that job. The optic measured a true 1.180 at both sides of the turret-cluster, mid-way from occular and objective, respectively.
Tube compression at 16 lb-in as measured by feeler gauges is roughly 10 thousandths of an inch (not accounting for ring-cap deflection).
I also noted that the ID of the ring bores on this mount is the smoothest I have ever seen from Geissele. I am suspicious that I got a mount produced as a near first-run on new tooling.
My constructive criticism is that the ring-gaps should be opened up by 0.01" to allow for tube diameter and compression variances. When one side of the rings goes solid before the other, clamping forces are NOT as they should be. This is readily evident when people tighten a LaRue mount criss-cross instead of bottom, and then top. It affects performance of the mount/optic juncture significantly, and can lead to wandering/inability to achieve zero. I do understand, however, that should Geissele open this ring-gap, it would be possible to over-torque the mount and cause damage to the optic of a potentially permanent nature, if an ignorant customer installed the optic using greater torque than recommended, exceeding the safety margin of the optic's maintube/internals. KAC uses screw-heads which are designed to strip at above 20 lb-in to combat this, as requested by their contractual obligations. Geissele has opted to do this, instead. Badger, Nightforce, and others rely on their customers to not be ham-fisted oafs. Take your pick, but when it fits, I like my Geissele's. They weigh the same, and are structurally more rigid, and let's face it...that sexy skeletonizing...
Also, a HUGE shout-out to everyone in CS at Geissele, and Jay, with Optics Authority, who I purchased this second K16i from at a great deal!