As usual I have been doing googlefu in order to try and learn stuff before forking out lots of money in a long term plan. Some of these things I (partially) knew before but I learned a little bit. Enough to make me more curious.

.45 ACP comes in either large or small primer variants.
.308 rifle brass also comes in large or small primer variants.
6.5 CM is yet another that is either small or large primer

I am sure there are others.

I am curious to have a conversation about this.

From what I understand the primer pockets on the small rifle stuff lasts a lot longer than large rifle. I watched one video where the guy set out to test and after X amount of reloads the brass was still fine except for the large primer pockets were too loose to hold a primer any longer and had to be tossed. When the same test was done using small rifle primers with the same load he hit X number of reloads and kept on going by a lot more so in theory he got way more bang for his buck for his quality brass.

If anyone knows or has resources about the small/large primer thing including what all parent cases it applies to post it up.

Note: I am hopefully soon to get into at least a couple of other calibers (rifle) and maybe out of another (pistol).

In that process I am considering on loading up on even more primers. I would like to stockpile primers even more than now. I am also considering throwing out a lot of old brass and investing in some good new stuff (maybe). This will depend on a bunch of things like caliber considerations etc but I might just take the plunge over time and say buy a lot of never fired cases at once from the same lot and just toss the rest.

Additional notes: I am considering getting out of .380 all together. It's nice to have--but it's just one more caliber and one I don't shoot as often. With .45 ACP it would be nice to have all my brass be the same primer size so I don't have to hand sort that stuff. For 9mm and really all other pistol calibers it would be nice to have consistent brass that will last a long time. Some of the mixed brass I am using for 9mm is great, thick, and robust. Other stuff is thin and soft. More than just accuracy it would be nice to just have a lot of consistent brass to work with that will last a while.

For rifle brass the life of the brass matters but also it's pretty important to get consistency from that.