(this is not saying that i think that high-velocity spore bullets would be a good idea, but crazy ideas sometimes lead to further developments, so here goes:)
yes, spores by themselves could probably survive as they have very little mass (like ants can survive falling from empire state building, and you cant even jump from a few meters without breaking somehting, its all about mass).
in a bullet of spores.... some would survive, but many would prolly die (i'm not going to guesstimate any percentages).
shooting a spawn plug... no, i dont think it would survive. the plug would break and expose the shocked myc which would die.
another reason for why its better to drill a hole for the plug is that it cuts the wood and this exposes the cut ends of the fibres to the myc, which can then spread along the fibres (look at a plugged log, the myc always spreads faster along the fibers).
now what use is this rambling? well, thinking about your ("crazy") high-vel idea led me to a possible "chop-spray tek" idea for establishing wild shroom patches.
Get a big carry-along sprayer (the pressureized type you carry on your back, see attachment) fill it with sporewater or LC. Also bring a small hand-axe. With this as you are hiking along, enjoying nature, and come across a dead tree, give it a good chop with the axe, and then spray the fresh cut with your media.
This gives the myc/spores a good head start in a fresh cut, with wide acess to fiberends. Much less of a hassle than drilling and plugging, plus one could also spray piles of leaves and stuff that one comes across while walking.