Until just recently I had only shot bolt action rifles.  Now I've built an AR15.  It functions fine, but the ejected brass is VERY HOT and is covered with a fine film of blackish grease/oil. Is the hot, dirty brass typical in a gas operated rifle or is there something wrong?  Any help would sure be appreciated.
Thanks.

What type of ammo are you using?  Brand?  Military surplus?

I'm using rounds I loaded myself.  Winchester brass, CCM primers, 26.5 grams Varget, 52gr. Sierra hpbt.

Very HOT brass, you bet and I got the scars on my right arm to prove it, (I shoot lefty), no problem there as ALL AR15 ejected brass is HOT, quite [b]common[/b].

Dirty too, here again this is [b]common[/b], in-fact the top round left in your mag will be dirty too.

Mike

I've never used Varget powders so I can't comment on that.  I have used Reloader 7 and Reloader 10 as well as several Winchester powders in my AR.  They are all cleaner than whatever military surplus that I've fired.

Even the clean burning ammo in my AR does have some black burnt powder left on the case and the cases are hot. I wouldn't say very hot though.

I would say "very hot". Catch one before it touches the ground in your bare hand and you will agree (let someone else shoot so you can grab the case right away). A bolt gun will do the same thing if you jack the bolt immediately and grab the case. I have seen three cases of hot brass down the collar and one of hot brass between the glasses and eyebrow by people to the right of the shooter. All four could not casually "tough it out" and all four had a bad blister.

Hot! Hell yes they get hot. Trust me that is very normal. As far as the black substance you are taling about make shure that you are not over lubricating your AR. It could be coming from your gas tube. I know most of the 5.56 ammo will leave a black soot after a few rounds. But It usally is not greasy.

Maybe he is using a suppressor on the rifle... mine come out with a light black soot coating, non-suppressed come out fairly clean... Using a shell will give you dirty brass also.

Don't get in a hurry to grab freshly ejected brass-------- IT'S HOT!!

There must still be some pressure in the chamber for the brass to be as hot as it is.

This is not a bug, it is a feature.  The quickly ejected brass helps to "carry" heat out of the rifle.  It is a means of heat dissipation.

WELCOME ABOARD! Ain't it great????

My cousin was sitting next to me while I fired my ar15. He got the bright idea of catching a few shells as they came out. Well, now he has a giant blister across the middle of his hand in the shape of a shell.

I guess I shouldve told him not to try it before I fired. ;)

Sounds like your chamber has too much oil in it and could use a cleaning.  Try that, and the shells shouldn't be that dirty when ejected.

A side effect of overlubing (as mentioned above) is that the case won't grip the chamber and will move back against the bolt face.  Not good. You can get pressure signs even with very mild loads. Sounds like overlubing, especially if you find oil on the top round left in the mag.

The heat is normal...there's just not enough time for the heat to transfer to the chamber, so the case stays hot.

I don't know a semi-auto firearm of any kind that doesn't produce enough heat in the ejected brass to burn the crap out of you...my GF still has a small scar on the top of one of her boobs from a piece of .22 brass that went down the front of her shirt a few weeks ago lol.  I still have a slight mark from a piece of 7.62x25 that bounced of the ceiling and lodged behind the right lense of my glasses...now THAT hurt!  

Everything I shoot in my ARs comes out a little to moderately dirty; however, it shouldn't be greasy or wet.  Varget isn't particularly dirty powder, but you will see some residue.  

Next time you go to the range, make sure there's a LIGHT coating of lube on the bolt/carrier...there shouldn't be puddles of liquid anywhere; also, at some point in the process, you should be wiping the sizing lube off of the cases before you shoot the ammo...you are doing that, right?  If you didn't that could certainly account for what you're seeing.  

Hot brass is normal. Try some factory loads and see if they don't come out fairly clean. Don't know anything about your powder, but none of my cases are like you describe, and I use a lot of different loads.

As someone else said, sounds like you're using too much lube. There's no place for an oily substance to come from unless it's from the lubrication of the gun itself.

YA HOOO! HOT AND DIRTY BRASS life is good

I have a little 22lr Browning that ejects out the bottom and those little suckers hit you in the forearm sometimes and are hot as hell!