I seem to deal mostly with Aimsurplus, SOG and Sarco for guns and Brownells for parts (you get a heck of a discount!).
All of the others are abit more expensive but have a better selection of hard to find firearms. I get a flyer (and I've forgotten the CO name but it has International in the name, I'll try to remember it) that has alot of Colt SAA's, Lugers, etc.. (great selection) but you can imagine that the prices go with it.
It all depends on what you are looking for, handguns or rifles. Rifles are realy inexpensive and you will need to buy at least 2 to 3 and then pick out the best one to keep, sell the other two (you are allowed to do this) and then get some more rifles and do the same. As long as you're selling for advancement of your collection and not for profit (you have to be careful on this one, it's a grey area but I take it to mean that if you make 51% of your annual income from selling C&R firearms, then you are in business of dealing in firearms).
Handguns are alot harder and more expensive to collect. Most new Cufflers start out with the basics, a CZ-52 and a Nagant. Sarco sometimes has the Star Model Super (9mm Largo, not 9mm Luger). If you look around you may find a Balister Molina at a decent price.
Most of the really sot after handguns, like the Lugers, Colt SAA's and even the Sistema's are either hard to find or expensive (or both). Sometimes you can find a German Mak but in all honesty it's cheaper to get the Polish, Romanian, etc.. Mak (the "modern" maks are around $130 and the C&R Maks are around $400).
Watch out on Lugers and Broomhandles. While they have a great value you have to watch out for people selling either "shot out" handguns (it's been shot so much that there is little to no rifling left), are in fair condition (very little blueing left, rust flecks or pits, hard wear and tear) that they want exc. prices for or the numbers are mismatched (generally called a lugerstein or mauerstein) and try to sell for original prices).
Also, some gunshops won't take your C&R because they are either unaware of what a C&R is or are too afraid to do a Dealer to Collector deal. Don't worry about it. If the firearm is something you really want then just do the reg. paperwork/NICS but if you can either do without it or find it in the flyers that you will get, then wait.
Cosmoline. That great, sticky stuff that every firearm that you purchase (not from places like Tombstone or some of the others, they clean it first) comes completely coated. You may get about 4lbs (or so it seems) of the stuff off a rifle, about 2 lbs out of a handgun. You will need to decide how you are going to get it off. Me, this is what I do:
Rifle: Hard to do because of the length. I bought a storage tub from wallyworld that would handle all the metal parts including the barrel. You will need something like this. First you completely take the rifle apart (so remember how it disassembled :smile: ). Fill the tub with a solution of hot water and I use Purple Stuff. Let it soak for awhile (long while) and then wipe off the cosmo. Get fresh solution and do it all over again until cosmo is gone. I also boil the smaller parts, especially the trigger groups and the bolt which houses the firing pin. You DO NOT want a gummed up bolt, rapid fires are not fun (and they are illegal whether you knew about it or not, this is especially true for SKS's).
The stock/Furniture is a real pain. The cosmo soaks in the wood and the best that I've found to do is either put the stock into a black bag and then drive around with it in the car for a week (basically, the sunlight melts the cosmo. You will need to take the wood out and wipe it down every other day depending on the heat ratio) or to put it in very hot water. DO NOT use Purple Stuff on wood. It will instantly suck out the cosmo from the wood, and it also sucks out all the stuff out of the wood and then you have a piece of kindling, it ruins it.
When you put it back together, you will get cosmo seepage from the stock, wood, take a wet towel with you to wipe it down.
Pistols: Take off the grip, field strip, boil it. These are easy
. After you boil it and the cosmo is gone, put into over at around 350 until dry (about 15/20 min). You will need to lube it very well as all the lube will be gone after you boil / cook it.
If anyone else has any information, please chime in.