When upgrading there is the question of whether the new piece of kit fits into your logistics or complicates them. Stuff like knives or camping gear typically aren’t an issue while guns and electronics can be. For example lets say Jim has an AR-15 or two (or 12) and down the road has a few extra bucks and decides to upgrade. He goes out and buys a nice Daniels Defense carbine. It takes the same .223 ammo, uses the same mags and load out gear he already has. On the other hand if he got a Steyre- AUG it would take different mags (though I do think there is an adapter kit). I would recommend at least staying in the same caliber. If he got a 6.8 it would rather obviously take 6.8 ammo that, however ballistically delightful it is complicates his logistics. Now I am not saying that you shouldn’t get something you want and can afford just that it is a consideration.
Figuring out how much ammo you want to have around is important. I wrote a post on this before which summed up my opinions: Personally here are the numbers that give me a warm and fuzzy feeling: defensive rifle- 3k, defensive pistol- 1k, shotgun- 1k, rimfire- 5k, hunting rifle- 1k. I am not saying those for any really quantifiable reason. They are just the numbers where I am comfortable. Somebody more narrowly focused on a short term disaster could probably half those numbers and be fine while a serious doomer with a big budget could double or tripple them.
As to the discussion of HP (and generally premium/ match type ammo) vs ball. I store at least a couple hundred rounds per pistol of quality defensive ammo and then a good amount of ball. For 9mm I got a case of these Federal Classic 115 grain Hi Shock JHP’s awhile back and checked that block unless I pick up a few more Glocks which regretably won”t happen any time soon.
For rifles I don’t worry about it much though I do store much premium ammo. Rifles produce so much energy that it isn’t a huge issue. The Wolf I have bought recently to feed the AK has been JHP. For a rifle I might (God forbid) use in a home I would rock JHP to help with penetration. Also generally speaking loading your “go” mags with something decent is smart. If you need to shoot the guy holding a knife to a loved one’s neck do you want the cheapest comblock import or Hornady/Winchester/Other quality name brand in the gun?
Anyway I have to wrap this up.