" Does anyone have a good method for storing the leftover pistol primers ? "...
I've stored loose primers in a variety of ways.. I usually would return extra, loose primers to the pkg. they came in..
unless I've thrown it away & don't feel like fishing out out of the trash can.. ( who knows what might be in there ?)
I ve put primers in small paper envelopes, smal plastic bags, & even dumped them in a plastic drawer, where I keep my reloading bench stash of primers.
I have a small clear plastic cabinet, with clear plastic drawers. Each drawer will hold 3 trays ( of 100) of primers. I have 6 drawers, so Have a drawer for SPP, LPP, SRP, & LRP's.. I keep magnum primers elsewhere, as I don't use 'em often. A few loose primers can be found in each of those drawers.
Never had an issue with primers going bad..had some I loaded recently that I'd bought back in the 80's.. LRP's as I rarely shot ( or had need to load LR cases)
All worked fine. Started going thru them quickly when I got a M1A, and even faster when I got an AR-10
Ever heard of Alcan primers ? I either bought or was given some Alcan LPP's.. loaded them in 45's..all worked fine, despite their age & ? storage history.
Never heard of Alcan ?, ..from a net post, " Alcan was bought by S&W/Fiocchi in the 70s and they discontinued the Alcan name by 1980.
Anyone looking for cheap primers might try the American Reloading website,... they may have the lowest primer prices you'll find.
Many of these bargain priced primers are foreign.. my experience is they work as well as CCI, Win., Fed.or any other brand.
I used Fiocchi ( years ago) when they were the only SPP I could find. Tried Tula / Wolf primers ( Russian) again, when primers were hard to find.. no issues with either. Lastly, I tried some Ginex LRP's, as they were the only LRP's I could find, & still cost $120/K when I bought them..
a bonus is the American Reloading's prices almost always include hazmat & shipping fees, which is a big savings.

Ordered from them many times, & never had an issue with the order or products I received.