I might be wrong, but don't think I am.
Generally when it comes to shotgun shells, a magnum shell doesn't have more powder, it has more shot in the shell. If you look at this list here for Federal shotgun shells (I chose a manufacturer at random): Federal Premium - Buckshot Ballistics
The 2 3/4" shell in 00 has 9 pellets, and a muzzle velocity of 1325 fps
The 3" shell in 00 has 15 pellets, and a muzzle velocity of 1210 fps
And the 3 1/2" in 00 has 18 pellets, and a muzzle velocity of 1100
So, those numbers would support my thoughts. You are getting more pellets, but your velocity is being reduced because the same amount of power is spread between more shot, and at the same time you are going to have more recoil.
Personally, I would rather have more rounds in the tube than more pellets in the shell for HD distances. You probably looking at less than 6" or spread at HD distances, so, it almost becomes a "at what point do I have enough pellets within the pattern too give high odds of hitting the vitals of a target." But I'd rather have that extra shell or two in the tube and use it for a follow up shot if needed.
My 870 takes 6 in the gun and it has 6 in the cuff, all 3". 15 pellets of OO buck and 41 pellets of #4 buck. It is NOT my go to gun in the middle of the night and the recoil is worse than standard shells, but for ME, it works. That is what you have to decide. If it works for YOU then it's good. Tangle's thread got to the point where my head hurt, but there was A LOT of information in it and a lot of different opinions. Would I feel under gunned if I didn't have 3" shells? No. 3" is what I have in the house.
The answer is bigger is better! My wife just told me so :tongue:
I use magnums, magnum size bottles that is, and 00 buck for HD.
I'm of the opinion that 2-3/4" standard #1 buck (or better, ie 00, 000) loads will create sufficient penetration/wounding to seriously impede a decently-sized animal, though this is primarily based on my shooting at a few sides of beef, a couple of carcasses and on third-party calibrated-gel testing results. I'm confident enough in the capability of that load, but then I haven't had to stop an aggressively-violent human felon with it before.
If still concerned, check with a handful of your regional police/sheriff departments to see what they load in their 12ga shotguns, then go with that. I doubt you'll be disappointed.
I was upland bird hunting with a guy that was using an O/U double barrel shotgun,we kept kicking up a covey of quail on his side of a hedge row and he started off boom boom,after about 3 reloads birds up....boom....boom #*#$&*( man this gun really kicks,Ruger Red label 12 ga.I said whats up,he was shooting magnum 3" in his gun,so I gave him some of my 2 3/4" reloads then looked at his gun and noticed chambered for 2 3/4",the chamber would accept a 3" shell but the crimp was opening into the barrel causing a restriction forcing the shot and wad down.No wonder his shoulder had a huge bruise,he's lucky the gun didn't blow up from the pressure
Not at all lots of people use reduced recoil loads.Lowe's
Either 2 3/4 or 3" shells will be just fine for HD. I don't think there's any need for 3 1/2" "Magnum" shells for defensive purposes, unless you feel the need for long-range defensive shots against marauding geese or turkeys.
On a side note....does anyone here have guard geese? :)
I'd consider a magnum load if I was using a .410, especially if I favored low-velocity rounds!