I assure you guys it's possible to shoot things at 100 yards. With a 6" Dan Wesson 22 revolver from a rest, I can usually keep 3 out of 6 shots in the black of a 50 yard small bore rifle target... What's that, 5"
With centerfire, I admit that I don't have a gun that lend's itself exceptionally well to 100 yard shooting. I've tried a couple of 1911s, Taurus PT99 (poor sights), a CZ IPSC Standard and EAA Silver Team and usually get one out of 5 or so in the black of the same target, generally all shots land on the 8.5x11. I used to have a 7.5" Super Blackhawk that was pretty easy to keep on target with.
Sometimes I wonder how 'on' our sights are at shorter distances. Slight problems at 25 yards become big problems at 100 yards. A 185 or 200 Gr 45ACP out of a 5" barrel should only be down about 4" at 100 yards if right on at 25 yards. Point is, with well regulated sights, very little holdover should be needed at 100 yards.
I said on another thread, shooting a normal handgun at 100 yards is a pretty Zen activity. You aren't so much aligning the sights with the target at 100 yards as much as doing pretty much the same as what you do at 25 yards but further out. If you know what to do at 25 yards, just do the exact same thing at 100 yards and you should be close. Larger reactive targets are the easiest and most reqarding. There's a reason so many people have a gong out there.