The only ammo I've come across that my A22 refuses to cycle is Federal BYOB - it's 36 grain hollow point. It will cycle any LRN ammo with near 100% reliability, even Remington Thunderbolt (which I think is the cheapest ammo you can buy). It will cycle most hollow points okay, but not not with 100% reliability, though my testing with HP's isn't as extensive as with LRN's.