Smith & Wesson
Model 66 Combat Magnum

I acquired this gun for self-defense. I was concerned about my ability to hit anything at ranges of 15 yards or more, because my ultralight snubnose is not ideal for that task. This should have enough weight and barrel length to shoot accurately, yet it is reasonably compact for carrying, even concealed.

Caliber:.357 Magnum
Capacity:6
Barrel Length:4¼"
Frame:K-frame
Sights:HIVIZ fiber optic front (after market), adjustable rear
Weight:36.9 oz

I purchased this handgun in 2021.

Status

I have selected Barnes VOR-TX 140 gr. XPB to carry in this gun, and this is what the gun is sighted in for.

Ammunition

Finding good ammo right now, during the pandemic, near the end of 2021, is going to be a huge challenge.

Barnes VOR-TX 140 gr. XPB
I vaguely recall that I tried this in my M&P 360, and it didn't like it. I want to say it keyholed and was very inaccurate. However, it's unlikely that it would do the same thing in a longer barrel. Lucky Gunner's Lab shows this bullet expanding well and over-penetrating a bit with 4" barrels.
Test: Best accuracy, and no muzzle flash. This is what I have selected to carry in this gun.
Hornady 135 gr. FlexLock Critical Duty
I scored a couple boxes of this at The Range in Ballwin. They had a little more on the shelf, if I like it. Evidently, Critical Duty is designed for use in full-length barrels, with deeper penetration through barriers. I really hope this is accurate, because in theory this seems like a great option. Lucky Gunner's Lab shows this load expanding well and just slightly over-penetrating.
Test: Reasonable accuracy. Minimual muzzle flash.
Hornady Critical Defense 125 gr. FTX
I'd definitely prefer a heavier bullet, but these are available now, so if they are accurate, then I can carry them for now. Evidently, Critical Defense is designed for use in short barrels, for limited penetration without barriers. Lucky Gunner's Lab shows this load expanding well and penetrating within the FBI standard.
Test: Okay accuracy. Muzzle flash. One stuck in the chamber.
Ammo Inc. 125 gr. JHP
A previously unknown name, but this is probably better than nothing, and it's available.
Test: First 6-rd group was 2¼" at 7 yards. Good accuracy, huge muzzle blast.
145 gr. Winchester Silvertip
Potentially too heavy of a bullet. I haven't seen ballistic test results.

Lucky Gunner's Lab .38 Special and .357 Magnum Self-Defense Ammo Ballistics Tests

It looks like my conventional wisdom of using 158 grain bullets is out of date. They over-penetrate.

Sights

The gun is (was) shooting a little high, but the rear sight is already adjusted as low as it will go.

I have replaced the factory front sight blade with an orange HIVIZ fiber optic sight. The old blade measured .235" high, and the new one is .268" high. I have raised the rear sight by .032" to more or less match, and now I will have to check it at the range.

Holsters

For concealed carry, I am currently using the a IWB holster from Blackhawk in size 8, and so far it has been working well.

I need to keep an eye out for other holster options. In addition to the IWB holster, I also need a hip holster can be carried cross-draw and be compatible with a backpack.