I have previously said that sorting by type is good and sorting by type and brand is better.
The above was my best guess at the time. Today I played a lot trying to get happy with some amount of mixing brands for cups and anvils. Very disappointing results. Castloader has made due with mixing because it is what he had. When he tries matched components, I expect he will find things easier and he will get better performance (few if any lost anvils, few if any need for second strikes, etc).
Bad combinations make "in plate" anvil seating by hand more problematic and less consistent.
I have changed my recommendation. Yes some brands may allow good results with some mixing. Do not bet on it until you have proven the specific mix you are interested in. My current best guess guidance is:
- Mixing type and brands will be a royal PITA and will adversely affect primer performance.
- All one type with mixed brands is likely to be a PITA and may adversely affect primer performance.
- Zero mixing may be something of a PITA up front, but is worth it.
If you are just thinking about reloading primers, and keep everything well sorted there is a good chance you will find that you will not use some of what saved. I used a lot of Fiocchi SPPs in recent years. Anvil removal is too difficult for me to bother with this brand of SPP. I also used a bunch of similar looking S&B primers that I consider great for reloading. Even if I had kept all my SPP separate from SRP, I would have lots of these two plus some other similar looking primers from range pickup brass. All in all I would end up tossing the good SPP with the bad because they were mixed.