Milt.
Yes. No weird combination wood screw/machine screw in a Charlin.

Tim, I believe our guy is looking for a guesstimate of what his gun should be worth, and not seeking info on useful loads. The Charlin thing is a sticky wicket that way, as fewer people are looking for a Charlin than a Darne, but, same as a Darne, there are some fanatics that are on the hunt. Based on what I see in the internet photos (always risky, but, that is what Ive got to work with) I see a Charlin with engraving, decent wood, and not in horrific condition. The barrels may have been reblued, but, it appears to be a sound looking hunting implement, in a useful gauge, and not the focus of a collection. The useful gauge part is the biggest downfall, as 12s are slow movers in these times. Id expect $1500-$2000 would buy it, if there arent any serious, undisclosed warts that turn up.
Most of the big dealers would have it priced near 3K. They would be looking at it, in their inventory, for years at that price.
If anyone else has a different notion, and a reason why, Id love to hear it.

Good luck with the sale.

Best,
Ted