I've only owned two handguns with "trough" sights, a Colt Dick Special and a Ruger Wrangler. Neither of them shot anywhere close to the sights. The Colt shot nice groups, high and left, the Wrangler shoots high/left, also, but the groups are excrement.
Correction, I also have a little Rossi .38 Special snubby that DOES shoot exactly to the sights with 158 LRN. I've even popped a couple of prairie dogs at about 45 yards with the thing, it's amazing, doubly so when most consider them to be "second tier" at best.
Truth is, I usually don't buy anything without adjustable sights. I like and need them.
