It happened again. Someone asked me what I thought the best caliber is. Granted they didn’t ask it quite that ambiguous. But it did raise the “insufficient information hackles” when I got the email.

The actual question was:

Tell me which caliber you think is best and why:  9mm, 40 S&W, or 45 ACP.

Had the question been, “Which caliber has the best stopping power?” I would have replied, “It’s tough to beat something chambered in 200 mm XM422 with the 40 kiloton yield option”.

The question isn’t quite that unbounded but still it’s insufficiently bounded to give an answer that is credible for even a fraction of the possible values of the unconstrained variables. One must really have more information about the use cases of the firearm before you can give an answer that someone couldn’t drive a Euclid truck through.

When someone asks a question like this what you really need to do is get the person asking the question to answer it for themselves. For all intents and purposes they already know the answer they just don’t know the proper questions to ask themselves. You can help them with this.

The top level question is, “What are you going to use this gun for? Recreation, self-defense, competition, all of the above?” One could drill down to a depth of three or more in the specifics for any of the answers given but here are few of the possibilities:

• What is your ammo budget?
• Self-defense against two legged varmints or four?
• What is the body mass of the varmint you need to defend against?
• One attacker or a mob?
• Which sport?

Everything is a tradeoff. The smaller calibers tend toward higher capacities, higher velocities, lower costs, and, obviously, smaller holes. With the larger calibers the opposite is true. Once you figure out your application then the caliber question should pretty much answer itself.

If you are interested in self-defense “stopping power” then I answered that question nearly 15 years ago and I don’t see any reason to update the conclusion where I agree with Greg Hamilton who says:

The entire discussion of “stopping power” is both stupid and irrelevant.   Statistics cannot be applied to individuals. People that need to be shot need to be shot soon and often. They need to be shot until they run out of fluid, brains, or balls.

If during the time you were reading the latest “stopping power” article you were instead practicing to save your life you would be far, far ahead.

Greg Hamilton
May 08, 1998

Of potential interest is what caliber gun(s) do I own and use and why.

I have guns in all three of the calibers in question. I almost never use the 9mm or the .45. The reason has nothing to do with the caliber themselves. It is because a .40 with 17 or 18 round magazines is the best choice for Limited class USPSA matches which I compete in. I can compete in USPSA and Steel Challenge with it and I can carry it for self-defense. I figure the odds of me using it in self-defense are pretty low but the probability of me using it in competition are near 1.0. And even supposing that some other caliber/gun would be better for self-defense the fact that I am going to be practicing with the competition gun is probably going to make up for the (questionable) fact that I wasn’t shooting the optimal caliber.

For some reason I put together another AR. I’ve had a pretty nice Colt’s Match HBAR for years, but I thought a light carbine would be good to have around for kids, new shooters and such. My daughter might want it at some stage.

This new one is cobbled together from nearly as disparate a set of parts as is possible. I think every parts group is made by a different company. The aluminum, railed gas block, for example, was knocked out on an old Bridgeport mill by Some Dude in Moscow, Idaho– I had to mount it on the lathe and trim it down a bit to make it clear the floating handguard, which is a used piece off of Some Other Dude’s AR. It’s all assembled as a mock-up right now. Mostly new parts, some of the metal being in the white. I wanted to proof test it before taking it all apart again, bead blasting it and giving it a finish of some kind.

Since none of the working parts had ever fired a cartrige before, I cranked off four rounds with the carbine held at arm’s length, one-handed, into a hillside (the thought had come to mind that the thing could blow up, and if it was going to do that I wanted it to happen far away from my face). Perfect function. All ejected cases ended up in a nice tight group off to my right, too.

After putting a few shots on paper at 25 yards, I took it out to 100 to get a good zero on the TX30 reflex sight. Here’s the 100 yard target. I fire two-shot groups for initial sight-in. One-shot “groups” would probably be OK for starters, but I like to get some sense of how I and the rifle are working together. The first 100 yard group is the one holer at the top of the paper, on the “1L” line. I’d thought that the TX30 had 1/3 MOA clicks like an ACOG telescope, so I over-compensated, putting the second group near the bottom of the paper. The TX30 has 1/2 MOA clicks, and the fact that the target was stapled to a log and was slanting back quite a bit accounts for the larger apparent error. Splitting the difference with a few “up” clicks, and a couple clicks left, the third group was pretty well dead on;

I have a padded steel rifle rest and some shooting bags, but I’m using them less and less. If you can’t use your vehicle, a stump, a tree branch, a rock, the ground or your knee, what kind of shooting are you practicing? In this case I was mono-podding, holding the 30 round magazine in my hand and resting the hand on the hood of the pickup. It works well enough. The truck bumper is OK too, or the tail gate, or a front tire steered over to one side. The tip of a longish snowshoe can make a decent place to rest your knee in a kneeling position… There are lots of options, so you can haul around less stuff.

Three consecutive two-shot groups of around 1 MOA and less. I be happy for now. Don’t ask me to repeat it. It was getting dark so I called it a day and let the dog out to romp around for a bit and get wet and smelly before the ride home. Ultimately I think I’ll want a solid 200 yard zero for this reflex-sighted carbine.

Dealing with “issues” while shooting is a good thing. In this case it was failing light, mosquitoes, my dog which hates gunfire (he ended up inside the pickup, and his moving around made the pickup, which I was using as a shooting rest, move just a little bit while aiming) and the fact that I’d ended up out there with no spotting optic so I had to trot the 100 yards back and forth to determine shot placement. That and there were people driving up and down the road, which was close enough I didn’t want to fire while people were so close and make them nervous. So I’m looking around, listening, swatting bugs, dealing with the dog, hurrying, and huffing and puffing a little. It’s an exercise in being very still while immersed in little stresses and distractions. That’s part of why I like rifle shooting so much. It’s wonderful. Sometimes it works out great and other times you chalk it up to learning. This time was like a dream, but I’ll have to figure out what happened to my 20×60 binocs.

This new light carbine is pounds lighter than my scoped HBAR rifle. I think it’s going to be one of my favorite shooters. I’d never “built” an AR before, and even though I’d had my Colt, and a Rock River, apart many times it was surprising to me how easy it was to cobble one together from parts. A fairly small child could do it, with a little bit of instruction.