Fascinating! One thing I have noticed is that when we bed with upward pressure most stock materials eventually take a "set" relieving the intended pressure over time. My SPS plastic stock did this noticeably. Groups opened up one weekend. I noticed the looseness right away. What to do? Well I tried a little experiment with Paracord. I left the leather pressure pad in the end of the stock under the barrel and wrapped—"whipped" the paracord as tight as I could to hold the stock to the fore-end of the stock. I'm pretty good with knots and my whipping is pretty tight and smart, I melted the ends leaving little tags so that the whipping doesn't undo it's self. Abracadabra all was well again and the SPS turned in one inch groups again.
There is a science behind the cycling of a barrel just as there is when we tune/spine our arrows to our bow draw-weight and draw-length. It's all about finding nodes and anti-nodes as we do when we increase/decrease arrowhead weight to stiffen/soften a shaft. Increasing/decreasing bullet weight can achieve similar results in a rifle barrel, though it's not visible like when we watch an arrow fishtail away from us when the shaft is too short/stiff.
Try the paracod trick. It's not beautiful on a wooden stock but actually adds a little grip to a plastic stock and doesn't look bad. Mine runs for about 2.5 inches in length, along in front of the sling swivel stud. I also added a little superglue to the cord/knot to stop it pulling loose.