Consider the expected failure mode, It's in tension in the chamber annulus. An axial split - hoop strength failure. A weak spot will go elastic first transferring tension around the defect. Which, of course,, we expect to be strong enough to handle the extra stress. So you can't really go by the thickens of an annulus without a defect. No? Except, of course, it's definitely safe if the thickness at the defect is at least a thick as a sufficiently thick n unaffected annulus, all else being equal.
When this problem was first presented to me, I looked for the minimum chamber wall specification and found that C.I.P. specifies 3.3 mm to 4.7 mm for the .308, depending on category of steel used. So 0.130" to 0.185". However, with the 700 we have the action surrounding part of the chamber, and the area in question.
Although I have a background in product test and development, the areas of material science, structural dynamics, and fatigue behavior are outside my realm of knowledge. In my ignorant perspective, a rifle chamber is essentially a simple pressure vessel but adding a blind hole is something that I don't pretend to understand in terms of design limits. I am very happy to say, "I do not know and will ask people that do!"
