BTA-Universe finding specific mechs

So I just started with Battletech Advanced - Universe, and am trying to figure out where to get specific mech variants so I can plan my path to get to the planet/faction space that has it. I'm looking at the Wiki and the faction+factory shop tables, and not finding some of the variants I really want (notably because I'm looking for endo-steel variants so I can't just clodge together something close enough). Is there a general store drop table listed somewhere, such that I can find out if it might spawn in the general store of the listed factions that use that variant? Also, in general, I'd like to know how the general store works, mechanically. If I have better reputation with a faction, do I get better rolls on the table? Are certain things locked behind reputation, other than the separated Faction Store? Do stores reroll after a certain time frame?

Otherwise, if I really want that variant, do I have to commit to fighting that faction to try and salvage one?

For what it's worth, I'm currently eyeing up the Axeman AXM-3N, which doesn't show up in a "find in page" search of the faction/factory tables, but one of the most notable users of it are the Steiners and I want to be allied with them.