One that most folks dismiss out of hand may surprise some-.25 acp, when fed the right ammo. No, it's not the best choice by any means-my primary,preferred round is .45 acp at a minimum.
But, I decided to do some tests myself a few months back with my old Raven, just to see if that round was as ineffective, inaccurate, etc. as everyone says. (whether they've fired it themselves, or not..)
The results with Speer 35 grain Gold Dots surprised the heck out of me.
I set up a 1" thick plank of pine inside the leg of an old pair of jeans-because I had doubts the round would even penetrate denim-much less the wood inside. Behind this I placed 3 water jugs,filled.
Fired one round @ 7meters-penetrated the wood and all denim, and all 3 water jugs, and embedded itself in the trunk of an oak tree another 20 feet past the jugs. Didnt expand, going through the denim and the pine-but.. penetration certainly wasnt an issue.
As to accuracy- from the Raven, and at 25 feet- could place all 6 rounds into a playing card, rapid-fired. Not too shabby I dont think..Not a whopping man-stopping load, but- if needed as a last-ditch weapon, I wouldnt hesistate to make use of it, provided I can get the shots where they need to be.
I can say this much- I was once a by-stander at a shooting over 25 yrs. ago or so. I took one .25 round into the back of my right hand.It entered along the back/top of my hand between my ring and middle finger knuckles, and slid along the back of my hand just beneath the skin, until just before my wrist and stopped.
At the time I thought I had just been grazed. But a while later,felt the lump of the slug in my hand-went to E/R had it taken out. Still got the round, actually. FMJ.
To this day, I occasionally have trouble with that hand. I lack as much articulation with it, am prone to bouts of tendonitis in that hand, and when the weather gets cold/damp I feel that shot like it was yesterday..sooo....
Another, non-handgun ,load that will surprise a lot of folks. .410 in #4 shot, and the 3x 000 buck loads. I hear a lot of "experts" in other forums suggest the #4 load to folks for home defense-claiming it wont over-penetrate, etc.
Or, the inverse- that it wont do much more than minor surface-wounds to the bad guy, etc.
I've tested these loads also. My results?: dont take that advice. It WILL result, someday, in friendlies getting shredded -downrange. #4 WILL -out to 25meters- penetrate almost every houshold interior construction material (sheetrock, studs, doors,and even ceramic wall tiles.) I even fired one shell through an old, metal, exterior front door. It completely went through it from 25 meters, and shredded the plywood behind it.
(Lest anyone wonder,These materials were laying around a property after an old out-building had been torn down to be re-built-no I wasnt just shooting up my or someone's home to test the loads .lol)
Same goes for the 000 loads. They grouped surprisingly tight out to 25 meters, and penetrated everything the #4 loads did, and then some.
Now, these were fired from an old NEF/H&R .410 single-shot. Not the new Tuarus Judges. I've not yet had the chance to try that.