I am starting a 7.62x39 build and have everything in order. The one thing that I keep hearing about is people that polish the feed ramps on 7.62 builds. I haven't read any good descriptions about what part they polish or mods they do to the feed ramps. Also pictures would be very helpful if any one has some.

Polishing not so much needed, but M4 feed ramps are a must.

In the case of the x39mm cartridge you want the barrel extension feedramps lightly contoured and polished similar to the first pic. below...
The second pic. shows the various types of feedramps, both receiver and barrel extension ramps (M4 style and non M4/rifle types)...

The main goal being to "blend" or countour both feedramps Into a "seamless" or continuous ramp(s) for smooth feeding...

Bottom pic. courtesy of AR15Barrels.com.





Most of the newer currently produced complete uppers in x39mm come with M4 ramps and
are generally GTG out the box and don't require much tinkering, save for possibly the firing pin.

I guess that would depend on the manufacturer.  Neither my YHM or Armallite rifles required polishing or feed ramp work of any kind.  Both ran just fine right out of the box.
 

I am using a Kies MK1 barrel and a Aero prec. Upper. Anyone have an experience with this barrel? Did you have to polish the feed ramps?

My only experience with Kies has been the ordering and waiting.  Mine is supposed to be here tomorrow.  I'm also interested in this since it's my first 7.62X39 build.

I'd shoot the gun to see if it works before monkeying with anything.  Like liquidmetal wrote, after a brief break-in period, I had no feed issues with my Armalite 7.62x39, and I didn't touch the feed ramps.

I guess I will run it first and see how it works.

I have the kies barrel and I used a LAR OPS-4 side charge upper receiver with the M4 ramps. They matched perfectly and I didn't need to polish or modify them. Make sure to use ASC mags (kies mags are ASC) and if you use the kies bolt get an enhanced firing pin.

Well I did get the Kies matching bolt but not the firing pin. I was just going to modify the colar on a standard firing pin.

Be careful not to remove too much.
Too much protrusion could lead to pierced primers.
I went with the cheap insurance and got the enhanced FP

When I had misfeeds my round always seemed to get stuck on the flat face between the two feed ramps. I took a chainsaw file and narrowed & rounded the face of this part. There was an earlier thread with pics of someone else doing the same, that same thread also has a pic of a Bushmaster 7.62x39 and that middle part between the feed ramps was gone, basically just one wide ramp. At the time I also only had one batch of ASC mags and the feed lips were tight, as they 'broke in' my feeding got much better, so I can't say my ramps were the only issue, but now they're much more reliable. The last batch of ASC mags were tight as well, first trip out they wouldn't always strip the first round but a quick tap of the forward assist and they went right in, no jams or misfeeds.

If any one knows of a thread about the firing pin mod. please pass it along.