I was out shooting today, and had some difficulty with my rifles.

I had a Norinco AKM-47S, Armory USA SSR85B-UF, and a CMMG Mod4.  The Norinco is (of course) used, but the other two I just bought NIB.  Today was the first day of testing all three.

The Norinco worked for about half a magazine, then the bolt kept sticking in the back position.  It would go forward when pulled back and released for a while, but then just stuck, and stuck hard!  I stripped it down to check for obstructions, but gave up and reassembled it.  My gunsmith said it froze up because the bolt was hitting the hammer incorrectly, and needed a little polishing and some oil.

The Armory USA underfolder failed to go into full battery, and hung up about half an inch two times.  That was right at the beginning, and then it stopped sticking and worked perfectly the rest of the day.  Only negative was the rust colored ooze coming out from every joint and seam.  My gun smith says it's just the residue from the bluing process, and I just need to rinse it in some Simple Green, or other cleaner like it.  It's not pitting or anything, just rust colored ooze.  Hopefully his suggestion will fix it.

The AR (and THIS is the reason for the post) worked flawlessly, until I chambered a round (I was shooting Wolf, I know, I know, but it's just so cheap!) and put it on safe instead of immediately shooting it.  I know better than to load a round in a hot chamber and letting it sit there too long, but I did it anyway.  I then walked 50 yards up range with the rifle, re-evaluated my target condition, and re-shouldered the rifle.  When I fired, it went bang, but didn't extract the spent casing.  The bolt stuck cold about half an inch from the chamber.  This has happened before with laquer covered Wolf, but not the new Polymer covered Wolf.  Well, I knew how to fix it, but it was time to go home anyway so I just stowed it away and fixed it when I came home (cleaning rod from the muzzle.)  

My question is: has this ever happened to those shooting brass cased ammo, or is this only specific to Wolf?  It's only happened to ME with Wolf, but before I start swearing off the stuff, I was just wondering if brass cased does the same thing in a HOT barrel/chamber.  BTW, the chamber was HOT!  It was 108F with heat index, and I had already dumped a couple mags at full speed.  

Three rifles went to the range, and all three needed serious attention or stopped working before the day was through.  

If you have shot a lot of lacquer coated ammo in the past, you might have lacquer deposits built up in the chamber... Ive had that happen with my AK... A good cleaning with some acetone will remove any lacquer deposits, if there is some of course...

i shot some of that ammo and i ripped the rim off of the round. cleaning rod knocked it out, first time i had a problem out of cases of ammo.

Happens to me with winchester white box .40 all the time.  

I've had steel cased ammo stick in cold chambers. I really don't think it matters what the ammo is coated with. I think the steel expands and doesn't contract like brass does thus sticking in the chamber.

A poster recently began a thread with a similar problem.  He shot wolf followed by brass cased ammo which resulted in a FTE and a case stuck in the chamber.  
I believe the answer (which made perfect sense IMO) was that the steel case wasn't expanding, allowing powder and residue to form in the chamber.  When shooter went to brass cased ammo the brass case DID expand...up against the crud in the chamber and the subsequent stuck case was the result.

I've never had problems with Wolf, but Silver Bear is another story.  I've got 100rds. of it at the house...it won't be making its way down-range.

clean the chamber

There are draw backs to cheap ammo, Wolf among others.  There's a reason it's inexpensive, so I don't expect it to be perfect.  It works the vast majority of the time.  There are situations where it doesn't work so well.  I use it for baseline testing, as it is underpowered and dirty and will stress a gas system that may be somewhat undergassed.  If it passes the Wolf test, it's likely good to go.

My rifle has a chrome-lined bore and chamber, is brand new so it doesn't have any built-up residue, and laquer coated cases have never been fired through it.

Oh well...  I guess it just goes with the Wolf territory.

Be careful.  The use of lacquored ammo can also result in a tighter chamber that raise pressures.  We have had guys use use cheap ammo in city owned weapons that created over pressure and resulted in major part failures with big price tags.  Also injuries can and have occured from blowing these guns up.