Bedding is the application of resin (some are steel, aluminum, cobalt, titanium, unobtanium and other exotic #### retaining materials) between the receiver (mortises, rear horseshoe tang, trigger housing contact points) and the somewhat routed out/ grooved stock surfaces.
The resin allows a supportive, unshifting, ultra reliable and therefore consistent shot placement interface (whew....

) so that the barreled action is solidly supported by the (hopefully stiff and NOT noodly) stock (NM spec is nice, super stiff , super FAT).
Illustrations and glass bedding M1's and M14's can be found all over the internet. I've stopped committing websites to memory. Google is your friend

...
I try to do a rifle or two at each M14 clinic we hold. Lots of fun!
Wobbles99 and HarryBlackbeaver are experts now!!

Look for their posts on this forum. Wobbles99 posted a long and detailed post somewhere here....
Hope this helps!
Barney
