I don't really think the reasoning to jump from a 3" to a 3 1/2" is solely range. will you gain some range? yes. usually in the 5-7 yard range but the big reason to switch is MORE BB'S. More bb's results in higher odds of hitting and killing your bird and allows a little more margin for error.
.... i.e., sloppy hunters can still down birds??..
(just kiddin')
But seriously, keep in mind that for years, many duck hunters were very successful with 20 ga shotguns.. Ignoring the lead vs. steel thing for a minute, a shotgunner must know his firearm and it's limits - then go hunting accordingly..
On a similar note, a majority of skeet shooters use a 12 or 20, due to 'more bbs' in the air - and that can help offset a slight error in lead.. But put a .410 in an expert's hands and he'll beat you rather handily.. It's all about lead, knowing range, and maintaining proper form..
BTW, best score I got in skeet with my .410 is 23.. Grrrrr..
