The first photo might look slightly more dramatic than it is, here area two more:
So I tried to remove the gas compression spring of my new office chair from the sockets to send it back. It’s firmly stuck in both ends, and I read the recommendation to knock it with a rubber hammer. I couldn’t find one, so I covered the gas spring with some soft cloths and tried a regular hammer - and was a bit too enthusiastic. Is this spring still safe to use? I’m guessing/hoping that that’s not really the outer wall of the gas cartridge? It is still working, extends and compresses smoothly.
That’s the cover/structural reinforcement. Get a rubber mallet for next time and reinforce the casing with something strong enough to keep it from failing.
What do you mean by reinforce? Reinforce the casing how? And do you mean that for a hypothetical next time I try to separate a gas spring from some other office chair’s base, or do you mean I should reinforce this one somehow?
Make one out of pipe, do a carbon fiber wrap, etc. figure something out.
A rubber mallet is handy to have but you do you