#1 buck makes a bigger wound channel than 00
Perhaps you mean collectively they make a bigger wound channel? 00 pellets are actually larger. A standard 00 load has 9 pellets. A standard #1 load has 15. Many experts (whoever they are) believe #1 offers the best combination of penetration and pellet count.
And just for further comparison, Federal's #4 buck has 34 pellets.
As others have indicated. Buckshot tends to pattern more tightly in open chokes while birdshot patterns tighter in more constricted chokes.
Regarding ammo selection, the Box of Truth website
has some interesting stuff regarding penetration and patterns.
Maybe check out the ShotgunWorld Tactical forum
for more thoughts on stocks or anything else related to defensive shotguns.