I have a C&R and have never sold anything I've purchased.   I have some "dumb" friends that would probably pay me $150+ for a $70 dollar mosin.  What are the legalities in this?  I imagine that I would use the profit I make off the sale towards other C&R's.  I'd like to pick up a bunch of K31's,  a few more M44's and another Mauser or two.  

Can you sell C&R guns you've purchased for a profit if it goes towards another C&R rifle?   How do you all treat situations like this?

Log any C&R you sell in your book.  It is my understanding that you can sell any C&R you have purchased.  You can even make a profit selling.  Example.  You buy 5 SKS's and decide 3 are good and you want to get rid of the other two.  Sell them off if you wish.  But.... this should only be to 'enhance' your collection not to earn $ or to sell your rifles off to your friends.

Thanks for the reply,, but do I have to include the sale price?  I do want to 'enhance my collection' and if I sell some rifles for a profit the better for me.   I just want to make sure everything is within the law and I just don't want to lose my license of something so simple.

I also have a queston regarding this as soon as my C@R comes in I will be buying 2 more k31's one of which I plan on selling to my niece at no profit she really likes mine and this way I will be getting a discount from aim and have the choice to pick the one that whould best fit my collection while allowing her to grow a little in the shooting sports. By the way she can legaly own firearms and is over 18.

Quoted: I also have a queston regarding this as soon as my C@R comes in I will be buying 2 more k31's one of which I plan on selling to my niece at no profit she really likes mine and this way I will be getting a discount from aim and have the choice to pick the one that whould best fit my collection while allowing her to grow a little in the shooting sports. By the way she can legaly own firearms and is over 18.

You are NOT planning on selling to your niece.  You might be thinking about buying two rifles and keeping the better one, but buying two rifles and planning on selling one to a particular person might be a no-no.  

I'm pretty sure that somewhere in your paperwork it says that it's not a license to do business, only to collect.  Buying with the intent to resell is illegal.  It seems to be all about the intent.  You can use the "buy 5 to get 2 good ones" line if you want, but no one from the ATF can hear you saying it to yourself in your head.  Your intent is obvious and that's what the law (or should I say ATF rule?) is based on.
What kind of friends are they that you want to rip them off?  I've offered to order stuff from Midway for my friends without me making anything on it.

it also states that you may sell off guns to "enhance" your collection, so it is perfectly fine to buy 5 and sell off 2 even for a profit. it also states that a gun can be given away as a gift so  giving it or even selling it to a family member is perfectly fine also. i log the price i paid and the price i sold my guns for in my bound book although i dont think its neccesarry.

You can sell pieces of your collection regardless of if you make a profit or not.  You cannot be in the business of selling guns, regardless of profit.

Yep, has this nasty warning right on the face of the License...in all caps/bold writing:

"THIS LICENSE DOES NOT AUTHORIZE THE HOLDERTO ENGAGE IN THE BUSINESS OF DEALING IN ANY FIREARMS."

They are still wonderful things to have though, and with minimal hassle compared to a 01 FFL.
And the full dealer discount you get from Midway and Graf & Sons for example make to easier to feed the old warhoses and buy reloading dies etc.