Just wondering if it is okay to shoot steel ammo in my AR15?

I have allot, I mean ALLOT of experience working with steel shot loads, and the effects of using steel shot in shotguns.

Personally, I would NEVER fire steel bullets out of any of my rifles. They only exception would be jacketed steel armor piercers, which I doubt I will be needing to fire. I certainly hope not.

Edit : Ooooops, am I misunderstanding ? You mean steel cased ammo. Steel cased ammo for cheap stuff. likely OK, but, I want the brass to reload. For those who do not reload, as per the article, and now we do have some definitive work to support the use of steel cases as a viable option. ( As BigHammer has so graciously provided a copy of )

I assume you mean the casing is steel not the actual bullet. Some people claim that steel casings will wear out your extractor, etc. faster...it's really not true. The steel used for the casings is much much softer that the steel of that parts in your gun; there is no problem with it. Steel-ammo is great for practicing since it's so much cheaper. It won't hurt your gun at all.

Q: "Just wondering if it is okay to shoot steel ammo in my AR15?"
A: For the most part, yes.

Here's an article that explains the ups & downs of doing so. :-)

The Box O' Truth:
Educational Zone #18 - Shooting Wolf steel-cased Ammo in an AR15
http://www.theboxotruth.com/docs/edu18.htm

Steel cased or steel core bullets?

Lots of the eastern european import uses a soft steel core with copper wash for projectiles. These are OK if the copper wash is thick enough. In my opinion --- the wash is iffy. A full gilded jacket may be ok- again it tends to run thin on the imports.

Steel cases? Steel tends to stick in chambers for a few reasons other than the coating they apply to prevent rust in storage. I have never had a problem with steel 223/5.56 other than a few split necks.
If you have a AR- that could get a stuck case now and then.

I have one AR that I built entirely as a fun range plinker. It's a DPMS 16" upper with a light profile and chrome lining. It has shot almost exclusively steel cased ammo for thousands of rounds with no problems. About the only difference is that when I shoot lacquered steel, I take extra time to clean the chamber since I have heard that it can leave deposits behind.

If mild steel cases are tougher than your AR, you should have got a better quality AR.

YEAHBUT-ammo is the most critical component of the equation. That's why we reload. I always went with Remington factory ammo as source for brass, but only because my boss told me it was the most durable for reloading. But I always found Federal the best for FACTORY rifle accuracy. Other than very expensive match grade factory that was still not as accurate as my own loads. EDIT BTW I found no difference in brass for reloading accuracy although some do really well with match grade brass.

Yes but you will wear out the barrel faster.