For over a decade I've been saving any boxer primed brass.  Mainly .223, 30-06, 30Carbine and a LOT of 762Nato milsurp or new M80 (from various countries).   I have saved up several sealed 5gal buckets.  

Last night I was sorting a year's worth of saved brass.  I have a varied collection of 762Nato semi-autos and several of them are pretty rough on brass.  Sometimes the necks are pushed in, the sides of the cartridge are pushed in or many (like the attached pic) with creased dents (these thanks to a 762 Galil Ace).

I have never reloaded but I may one day.  Obviously I have way more brass than I'll ever use.  I may sell it off in bulk some day.   To get to the point: Does the process of reloading straighten out the case?  To what degree and where?  I know necks are able to be reshaped.  How bad can the body of the brass be before it's not able to be reloaded  ?

Fired brass is generally very cheap, mostly free in my world. Those cases pictured could be straightened out by firing them, but it's not worth the bullet, primer, and powder to do so IMO. I would personally scrap those. No amount of running those through a die will take those dents out.

Okay but do dents or slightly misshaped cases affect the quality of a reload?   Or is it fine , just ugly?

They may not be Xs, but they'll shoot tight 10s.

They will shoot fine and the dents will fire form out. One thing that I wonder about though is if the dents are too large could the powder in the new load end up compressed and drive pressures up to dangerous levels?

I would recycle those. IMO there is no reason to risk a case failure from a badly creased case.

I would try to play with recoil springs, buffers and powder selection to stop the brass from getting hammered so bad.

Keep your M80 brass separated from any commercial .308 brass. The load data is a full 2.0 grains lighter when using the thicker M80 brass. Many published starting loads are maximum in 7.62x51mm brass.

AK's dent cases as do the HK91. The Valmet had a port buffer sold through RTG and some guys modified the top cover of the Galil to make them fit. I don't see those on their website any more.  

As for the brass you showed I'd load them up. I've reloaded probably a thousand cases with similar dents and what ever the sizing die didn't straighten out, firing them again did.

I don't shoot X39 much and not through an AK variant so can't say how many cycles they could expect to be fired before they need to be retired.

I would save those for a semi auto that is rough on brass and not match grade accuracy. The dents will iron out some when ran through a sizer. They will be gone after firing. It makes good brass for practicing less than ideal shooting scenarios or positions where accuracy does not matter.

Thank you for all the info.

FWIW I did just put a KNS piston on this 762Nato Galil Ace (Merry Christmas to me from wife) and I've got it dialed down to toss brass out about 3 feet with literally no dents or blems on the brass.

Meanwhile, I have several 5gal buckets of .223, 30-06 and 762Nato once fire brass that I've been picking up for years. More than I'll ever reload but definitely of use to reloaders. Gotta be worth more than scrap. Disclaiming that up to 20% of the 762Nato may have dings and dented case mouths how might I best go about selling? Maybe 200rd bags at how much $ each? Shipped $? Or package/sell via as many as I can stuff in a USPS flat rate box? What are they all worth per round?

The dents go away once you full length size them. Nothing to worry about.

Small ones, yes, after sizing and firing. The big dents and creases in the photo might be a problem, perhaps cause an over pressure or case rupture.

They can be fire formed back and then full length sized as below, but hardly worth the effort for .308 or 7.62x51. If a rare/oddball caliber I'd try fire forming them.

http://bulletin.accurateshooter.com/2017/02/how-to-fire-form-brass-without-bullets/