My point about the shim RC was that I work with shim stock on a daily basis. .020 of any material does not bend and conform to sharp angles and shapes without some serious force. In my opinion when you placed the shim between the ramps, It worked better due to ta false effect of the shim not following the shape of the rear baffle. I'm sorry but from a mechanical perspective the opinions being expressed here are not indicative of common mechanical understanding. Not to say that anyone is dumb, quite the contrary. Just lacking in mechanical knowledge.

About PE, there is no reason to have PE if brass never gets stuck. Much of what you say is true about other factors being involved in some instances. There are many things people can do to a chamber that can cause cases extraction effort to be above normal. The responsibility of the gun owner is to keep sand and oil out of the chamber. It is the responsibility of the smith to get the correct finish in the bore. What is left is case design and pressures. WSM's for example will grow in the web area and will begin to make it difficult to extract after a few firings of the brass. The solution is new brass not a shim, screws or machining obviously.

Here is the kicker, If you can rotate the bolt 90* and the case does not move, Then PE is the first place to start.

It is not about me or you being being right. It is about accurate information. I could be wrong about the whole issue but If you are going to take a different position be deliberate and more precise in your argument so we can all benefit and learn.