Thanks for all the helpful advice.
With Poulin, Amoskeag, Holt and Rock Island all having auctions scheduled in the next six weeks or so, jumping in is tempting. That said, so far I've seen stuff that is interesting, but nothing I've gotten really excited about. I will say that the gun market seems kind of like the antique car market at the moment--there's a generational changing of the guard, so things are in flux. But I'm not a collector, much less an investor.
One question about Holt (and Rock Island). They seem to have a two track system--so there is an auction of premium lots, and then there are secondary auctions (sealed bid in Holt's case, more frequent in Rock Island's). How do consignments get allocated between the two, and from a bidder's perspective, is condition going to be less of an issue in the 'main' event? I noticed that for last summer Holt's sealed bid auction had an endless number of AyA's and various other Spanish makers imported into the UK starting around 1970, although from the pictures some of that merchandise seems a bit tired. The realized prices on that stuff was quite a bit less than you see here in the States. Made me wonder.
Amoskeag also has a silent auction. Generally its stuff that isn't worth putting in the regular auction either due to time or condition. Most auctions seem to average about 100 lots an hour, less at the beginning, maybe a bit more as the auction comes to end.
Rock Island will sometimes run a one day online only auction of things not worth putting in their multi day auctions.
Regarding the silent auctions, make sure to really read the description. None of these auction houses are going to lie, but they are going to accent the positives over the negatives.