As noted field loads tend to pattern much worse than purpose built SD/HD commercial loadings, and don't really do anything for you. As was just mentioned #1 buck in a 2 3/4" shell is a great compromise if you want more pellets, and still want 12"-18" of penetration. I wouldn't go for anything with less penetration for SD/HD. If you want to extend range (usually the arguement for 3" or larger shells) I'd recommend one of the modern loadings utilizing technologically advanced wadding like Federal Flite Control as it can (choke and barrel depending), keep your patterns very tight out to a significant distance (we've had a sub 4" pattern at 25 yds out of a 14" short barrel shotgun. If you need true extended distance, basically needing to move into rifle distances, slugs can provide that while having much less of an over penetration problem then people assume.
-Jenrick