The MOD published guidelines on what a lubricated round would do in a smelly and why it was was to be avoided when proofing. The increase in bolt thrust was statistically significant to say the least.

Thanks, I would be surprised, if such an experiment was not done. I wonder of the taper on a case wall would exacerbate the situation, and a modern straight walled case would negate the problem?

Thanks, I would be surprised, if such an experiment was not done. I wonder of the taper on a case wall would exacerbate the situation, and a modern straight walled case would negate the problem?

I'll try and dig the document out. It dealt with the procedures for poofing SLMLEs and was really interesting in a number of ways. One was that the Enfield action was up to a fair bit more pressure than legend would suggest. Another was the very strict instructions around chamber and cartridges being completely free of grease or oil due to the enormous increase in bolt thrust invalidating the results if they weren't. 

The MOD published guidelines on what a lubricated round would do in a smelly and why it was was to be avoided when proofing. The increase in bolt thrust was statistically significant to say the least.

Thanks, I would be surprised, if such an experiment was not done. I wonder of the taper on a case wall would exacerbate the situation, and a modern straight walled case would negate the problem?

Yes, the taper does make the problem worse.

Case taper and pressure are some of the factors that govern ease of extracting a fired case. If there is no taper, cases from mid to high pressure cartridges are difficult to extract. For that reason there are very few straight (parallel) wall cartridges. Those that exist are low pressure with a few exceptions. Most notable is the 5.7 which has a dry lubricant on the case to aid extraction. Cleaning those cases in a tumbler removes the coating and makes them unusable.

Excessive taper causes high bolt thrust and a loss of useable case volume. Also makes it difficult to design high capacity magazines.

Most historical designs have a pronouced taper. That is why PO Ackley could improve cartridges; "Ackley Improved" or AI. He found that reducing the taper and changing shoulder angles not only gave increased powder space, but also allowed a slightly higher chamber pressure.

https://gundigest.com/gear-ammo/ammunition/experimenting-with-bolt-thrust

I found this quite interesting in the subject of bolt thrust and case taper.

I think bolt thrust is a massive demon in the dark for most people, never seen, never exposed, just there waiting. It is such a huge, massive, catastrophic potentiality, sitting there - right nexter your management center.
                                Every shot.