I would attempt to fire some in an empty case just to see if these are still good.. I'm not suggesting you use them for actual loadings but I keep old primers (properly stored in empty primer boxes) and use them in reduced loadings for fireforming brass. For forming things like 30-30AI, 357 AR, or converting 303 Brit into rimmed 35 Remington, I use these scrap primers, a moderate powder charge (from the Lyman Cast Bullet Loading Manual) and a cast bullet. Not trying for accuracy or velocity, just trying to fireform a piece of brass. A word of caution here! Loose primers stored in bottles can detonate (explode vioently) if dropped and send primers in all directions (thimk Claymore mines) with possible seriously injury to anyone nearby. If you do keep them, store them properly.
Can you expand some more on why it is a bad idea to try and sort these into large and small? Many people seem to use rifle for everything without issue. My concern would be using pistol on rifle rounds or a magnum primer on a hotter load. With the mixed primers you may not be able to properly distinguish. I salvaged about 300 mixed from a deceased relatives bench. Still sitting on them.
Why take chances?
just use them for target practice - I have mistakenly loaded 223 rounds with SPP and they shot fine
l have also used LPP for my rifle rounds in a pinch and could not detect a difference
some rifle primers may not fire in some pistols but other than that I don't see any hazard in using them
If you are a bench shooter you wouldn't even be asking the question
Meh, I'd load up 20 or so with medium loads and try them out in a solid pistol. If they work they work. Primers aren't going to blow up a pistol if you aren't pushing powder limits.
Will a damaged or contaminated one contribute to incomplete ignition though, squibs or light loads that don’t exit the barrel would be my biggest concern
Which a shooter should always be aware of anyway. I've had that happen with factory ammo.
Anyway, like I said. Test a batch...slowly. If they are good they are good.
Pistol primers are of lighter construction (the cup) and are shorter than rifle ones, a good example is the S&W 500, the first production of ammo saw pierced primers (too much pressure) so they re-tooled to produce the brass to use rifle primers and put out a warning not to try and use rifle in the older pistol brass, all new brass is for rifle primers. putting a rifle primer in an old case that used pistol ones might jam the gun up because of the shorter primer pocket or worse!
Jack, This explanation makes more sense. Like I said, do not ever want to use pistol primers near rifle loads but had never heard about the brass issue. I know some of my 45 brass of all types is much older manufacture. I am still just sitting on these primers looking for a good use of them. Hate just throwing them away 
