I'm using old-school ammo and I'll tell ya why.
My EDC is 10mm and my choices are slim.
I wish to stick to factory ammo.
I could go the boutique route (Double Tap, Buffalo Bore, Underwood) but these are either not available anywhere other than ordering online and/or pricey. Doesn't mean I won't elect to carry these at some point in the future, but it's one of the reasons I don't currently.
The "10mm ammo" made by the other big sources simply doesn't measure up to the Winchester Silvertip, in my opinion. The Federal Hydra-Shok is the worst, running a horrible velocity that isn't nearly up to spec for the round. The Hornady offerings are better than many, but still not quite as good as the Silvertip, in my opinion. But I'd carry the Hornady 180gr XTP in a pinch.
The Silvertip was the high-tech bullet choice in the early to mid-1980s, and it's a sad state that the big ammo companies won't dedicate any development dough to 10mm, but it runs a good speed and I can get it and I can run through a couple boxes on occasion, so that's what I'm carrying.
Attention Brass rats and other reloaders: I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.