Jeff,
Well, kinda', but, not exactly.The extension on the barrels, and it's "rising bite" (to steal a term from conventional guns) are actually a secondary lockup. The primary is the toggle driven cam that meets the wedge under that sliding breech.

The "Automatique" word stamped on every Charlin I have ever seen refers to the selective "ejectors" (stealing another word to use in description of something similar, but, not identical) which extract spent shells, but not fired ones. There is no "lockup" per say in a Charlin-it is an over-the-center device, pure and simple. Force on the face of the breech will only hold the breech closed tighter. Sometimes, a knucklehead out there will shove hot, 2 3/4" US spec loads into a 2 1/2" chamber Charlin and see the toggle has raised slightly after the shot. This usually causes the knucklehead to soil himself and pronounce the gun "unsafe". However, nothing could be further from the truth. The last little bit of travel in the opening lever, or key, in a Charlin is an "interupter", (stealing a term from Star Trek!) which keeps the gun from firing until it is completely closed. Hot loads in short chambers can cause the key to move into the interupted position, out of battery, and unable to be fired again.

There are dozens of Darne patent "clones", (hell, let's steal some medical terminology, while we are at it) sometimes marked, often nameless, that were produced in the St. Etienne region after the first 1894 patents went public in France. Most of these copies are very good quality, but, as with any gun, judge it on it's individual merits. There exist Purdeys that are not up to the usual standards of that firm, and there exist Darnes and Darne clones that fall into the same catagory. If you can't figure out the difference, then hire someone who can, before you throw a pile of money at any gun. What is most often wrong with sliding breech guns is that someone who shouldn't have been has done some work to it. They are quite different than any other gun, and even good gunsmiths get stymied on them, sometimes.
Best,
Ted