That strikes me as another problem. A significant portion of thrust is - as I understand - controlled by the cartridge case expanding again the chamber walls. At 80,000 psi, that might cause some problems requiring mechanical lockup to be stronger. Strikes me as demanding a certain action.
The idea that cases are strong, and actions are weak, and that the case is supposed to carry load to reduce bolt thrust, is an Army coverup over a century old. In comparison, the Chinese COVID Lab coverup is a short term piker, and even less successful. Pre WW1 the Army was building M1903's in factories which the only recorded temperature gauge (a pyrometer) was used for heat treating springs. Every where else steel temperatures were judged by eye. This was a consequence of under funding, and a management that did not want to know, so they were in denial. When receivers, bolts were over heated, that is burnt, in the forge room, the heat treat ovens, etc, and these structurally deficient rifles parts got out into the field, and blew up, the Ordnance Bureau denied there was a problem. And created the misdirection that the receivers were blowing up because of greased bullets. The bullets were greased because grease prevented cupro nickle bullet fouling.
The smart shooter of the era purchased a grease filled tin, with a little hole for the bullet, and the shooter dipped the bullet in, gave a twist, and fired the round greased.
This is massive over greasing, but something I did .
one the left before, and on the right, after firing.
all greased and fired
and what is noticeable, is that grease flows down to the base, and the sidewalls are coated with grease. Obviously the case is not sticking to the chamber, the whole case is floating in grease.
When "perfect" Army rifles firing "perfect" Army ammunition blew up on the firing line, the Army blamed the grease. The logic is simple, rifles fragmenting on the line can't be due to anything the Army did.
Reminds me of what Boeing said about the two 737 MAX crashes. The planes were perfectly designed, and perfectly built, so the crashes had to be pilot negligence! . And if you are a Boeing employee, you agree, because you have drunk the kool aid. All human organizations believe their own propaganda. Those that don't drink the kool aid are cast from the kingdom.
Anyway, the idea of "increased bolt" thrust being a danger started then, and has been promulgated by generations of in print gun writers to hundreds of millions of shooters. The cover up has legs. But it is false.
the case is a gas seal, not a structural member. The case has to be supported or it will burst. That was an opps!
If the case is stretched, it will rupture. No one weakens an action assuming that the case takes some of the load. For example, what is that number? By how much would an action designer weaken his action, assuming that the case carries the rest of the load. And what happens if the round is wet, or the barrel is cleaned and oiled?
And, why would anyone want the case sticking to the chamber? If the case sticks, breaks the extractor, or rips the rim off, it has to be knocked out with a cleaning rod, or dowel. Not a good idea for a repeating rifle.
And surely, the sidewalls of those plastic cases can't take much thrust off the bolt, the joint will fail.
And what about caseless ammunition, surely that could not work, as there is no case to take the bolt thrust.
In my opinion, the 85 Ksia rounds are going to be trouble! Just take a look at the lower grade of steels and see what their yield strengths are, which is around 80 kpsia. So bolt lugs are going to have to be made of higher grade steels, which require strategic alloys, such as nickel, vanadium, molybdenum, etc, and that stuff comes over oceans, which during one war, was filled with U boats and sharks! Why would anyone assume that the oceans will be friendly in the next war?
Combining the industry capacity of China, with the raw materials of Russia, and the US will be starving for food and materials.
And, the receiver seats have to be built out of high alloy steels, and heat treated, so the fatigue life will be less. When steel is heat treated to be hard, it loses toughness. That results in a shorter time to failure with loading cycles. On the AR forum, one poster asked about bolt life, and a lot of AR15 bolts start cracking lugs around 10,000 rounds, some last 30,000 but they are made from special steels. I predict with 85 Kpsia rounds, the lugs will be cracking sooner!
Anyone remember those traffic classes we used to take, that had films titled "Speed Kills", or "Speed is not your friend"? Similarly, high pressure is not your friend either. The pressure curve has an exponential slope, and with cartridges running 85 Kpsia, I predict blown breeches and barrels when the pressure curve spikes due to temperature, fouling, old gunpowder, rat's nests in barrels, etc. Things go bad, a lot faster, at high pressures.