Last year I bought one of those neat little NAA Mini Revolvers, which shoot .22 & .22 magnums. Just to get this out of the way, neither this or any other small caliber pistol will ever be a carry or self defense gun for me. After buying the little blaster, I discovered that ammo makers were making "self defense" loads in .22 mag (WMR) including Hornady Critical Defense, Speer Gold Dot and Federal with Speer TNT bullets. All claim to be controlled expansion and hot. In my unscientific tests, they all penetrated and expanded well in test medium. The Federal expanded the best for me, to about 9mm diameter and penetrating about 12 inches from the NAA, 1 5/8" barrel. The Hornady Critical Defense ammo penetrated well and expanded as advertised. The first time I shot some, I experienced a 20% failure to fire. Some fired on a second strike, and some others did not. Other brands of ammo (CCI, Speer & Federal) fired 100%. I contacted Hornady, who paid for me to ship the remainder of the box back to them, and they replaced it with two boxes from another lot number. So far, so good. Because it was a brand new gun and fired all other ammo 100%, the gun was not suspect. Fast forward a couple of months and this past weekend, I get a chance to shoot the replacement ammo at my secret laughing place in the Tualatin Mountains. Once again, I get about 20% failure with the Hornady stuff, but all other brands work great. The hammer strikes on the casing rims appear light on the Hornady ammo, and "normal" on the others. Being a loyal member of the NAA discussion forum, I searched the various discussions, where I learned that in the opinion of some, Hornady makes their cartridges with thicker brass which causes the hammers to not strike the rim as deeply as others. Now for my question: Has anyone else had similar experience, or know if Hornady does in fact make their cartridges using thicker brass?