They 'used to be' made at diff factories. I haven't kept up with the situation lately. There were diff 'Lot #" sequences for the diff factories so you could tell where they were made. Here's an old thread ( 2008 ) on 'another world' forum about this. Just fill in the dots -> http s://www rimfirecentral com/threads/cci-standard-velocity-0032-vs-0035.251124/
Here's the relevant info - "... Specifically, I asked about the product that is available in the shops now (i.e., I wasn't asking for a history lesson, so this might not have been the case a year ago). I was told that when 0032 and 0035 are both made at the CCI facility in Idaho, they are identical. However, occasionally 0035 is made by Federal at their Minnesota plant using Federal components, resulting in a slightly higher velocity.
So how can you distinguish Federal 0035 from CCI 0035? The headstamp is C on both versions. The only way to be sure is to check the lot number. CCI lot numbers begin with a letter, e.g. "B24P16". Federal lot numbers begin with a number, e.g. "2BV593". This jibes with my fairly small sample of CCI and Federal ammo. ... "