The HK trigger package options are not user-serviceable. If you want a package, order it. Here we see the single-action safety and double-action decocker option.

One thing that can be said about the HK modern trigger system on the USP models is that it is uniformly nice. The Mk 23 in particular, in single action, was very useable. I've shot a lot of matches in the past with custom guns whose triggers were not as crisp and clean as the Mk 23 had right out of the box.

Magazines for the Mk 23 and the Tactical use the same tubes. The Mk 23 magazines will lock into the Tactical but not the reverse. The baseplates on the Tactical magazines strike the Mk 23 frame before the tube can lock in place. If you want to use your HK 45 magazines interchangeably, you'll have to install Mk 23 baseplates on them.

The safety on the Mk 23 is worthy of that overused superlative in the modern era: unique. The trigger action is both a double action and a single action. The safety is an ambidextrous lever that blocks the action only in single action. If you are using it as a double-action-first-shot pistol, the safety lever won't move up. Once you have it cocked, you have the option of either engaging the thumb safety or using the separate decocking lever to lower the hammer--that's right, both a single-action thumb safety and a separate decocking lever. When the thumb safety is on, the decocking lever doesn't move. I've seen a lot of handguns, and I don't recall any other that has this combination.

Considering the specifications laid down by the committee, HK did a superb job with the Mk 23, superb enough that it won the contract and provided the government with a truckload of handguns larger than some compact submachine guns.

The Compact and Standard are not just smaller and bigger pistols; there are differences. Here you can see the OD green compared to the gray.

As much fun as trying to match the colors was, all it proves is that color-matching is an art. Trying to get an ink color, which will coat paper, matched with a color that is suffused throughout a polymer resin is like comparing apples and oranges.

All the USP models and the Mk 23 had two things in common: a lanyard loop in the bottom rear of the frame and a mechanical lock built into that lanyard housing. Lanyards are one of those old military features that are new again. In scrambling over destroyed buildings, through thick jungle or when completely exhausted, if some necessary piece of military equipment isn't securely attached to you, it is likely to come up missing.

The Tactical is a big gun, as befits its 12-round .45 ACP capacity and Mk 23 heritage.

As for the mechanical lock, it is one of those things necessitated by attorneys and legislators. The HK method needs a special two-pronged key to turn it and won't go on by itself. So if you never knew it was there and never used it, you'd never notice it. If you do need it or want it, drop the magazine, and look in the mag well, toward the backstrap. There you'll find a round button with two holes in it. Use the key to turn the button so the holes are vertical, and the hammer is blocked. With it locked, you can't work the slide or cock the hammer.