For me, forget the cost comparison, its the WEIGHT. If a time comes you have to carry the ammo on your back, whats 3000 rds of centerfire vs. 3000 rounds of .22? Nuff said!
And an extension of that is that by the time you get off three rounds of centerfire i can get off six of .22--lets say from a rifle. And you know what, that fellow (or other animal) you shot is a dead man walking. 22-cal jumps and richochets all over the place inside a body and even if that fellow who you encountered out in the forest gets to a hospital soon, chances are he isnt going to make it for all the damage a .22 has done.
I have larger calibers which have a better drop dead factor but considering ammo cost, ammo weight and ability to become proficient sooner i choose .22 first even with its delayed-reaction death specs.
If anyone doesnt believe a .22 is a serious weapon, dont listen to me, just go to any Emergency Room and take up the topic with a doctor then come back here.
Slim River Carry Slings for Henry AR-7