For some background, I had recently finished building the rifle. One of its 922r compliance parts is a U.S. manufactured barrel--plain steel, no chromium lining in the barrel or receiver. Although 5.45 mm ammunition is relatively inexpensive, it is not common. Most of what is available is East bloc military surplus, and so that is what I had to test the weapon. As you may or may not be aware, the Soviet-era ammunition is steel cased, with a green lacquer coating, and a red seal around the bullet and primer.
I had test fired the weapon several weeks ago without malfunction, putting approximately 100 rounds through it. Cleaning afterward was a quick pass through the barrel and chamber with cleaner, oil, and dry patches, and a general wipe down.
With one thing and another, I did not get back to using the weapon until this past weekend. Temperatures were in the mid-30s, so chilly but not
I made some attempt to remove the casing, but the cleaning rod I had was too short, and the multi-tool just couldn't give me enough leverage to work the casing out. So, I put the rifle aside and we shot some other weapons.
After returning home, I used a brass cleaning rod and used a light mallet to try and tap the case out. No good. I tried a heavier rubber mallet. No good. I tried a 16 oz. ball peen hammer. No good. I sprayed WD-40 down the barrel and let it sit overnight. The next day, I tried again with the rubber mallet and still couldn't get the casing to move.
Doing some research, I discovered that this is apparently not an uncommon problem when using the lacquer coated, steel casings. Apparently, when the chamber gets hot, the lacquer can melt and begin to build up in the chamber. Bits and pieces of the red sealant can also get stuck to the lacquer coating the chamber. So, with either a long shooting session, or a later shooting where this lacquer didn't get adequately cleaned out, the lacquer can build up to the point that a shell can get stuck--i.e., glued--in the chamber.
Obviously, in the future, I will need to pay particular attention to the chamber, and use a brush to make sure I break up and remove any lacquer. My only excuse for not already doing so is that (a) I don't shoot ARs, so I'm not used to having to do a full-out, brushes and solvent cleaning every time I shoot, and (b) I've used steel cased ammo for nearly 20 years in other rifles (albeit, with the original military chrome-lined barrels) and never had this issue before. Obviously this weapon, either because of the lack of chrome-lining and/or tighter tolerances will require a more careful and detailed cleaning regimen.
As for getting the case unstuck, my research indicated that the best method was to use a penetrating oil down the barrel to soak the casing and lacquer, and let sit overnight, then tap out with a rod and mallet. The general consensus was to use Kroil brand penetrating oil. Obviously, the WD40 had not worked.
I went to a nearby hardware store, but they did not have any Kroil in stock. They did, however, have Blaster PB "penetrating catalyst." I took that home and sprayed it down the barrel. The label indicated that just a few minutes should be sufficient before giving a try, and so I thought I would see if the advertising was true to its word. A few minutes later, after a few hard taps on the rod with a mallet, the casing was free. The Blaster PB was true to its advertising and instructions.
A few lessons learned, and the discovery of a new product for cleaning and lubricating firearms, so there was a silver lining behind this whole thing. And I was glad to learn of this issue now, rather than later under different conditions.
Update: A review from Survivalist Blog on the Bulgarian AK74.
Second Update (1/25/2012): A few weeks ago, I had posted about a failure to extract issue with an AK74 using a U.S. made barrel. The chamber was covered with what appeared to be a uniform brown coating, which was obviously what was causing the cartridge to stick. I thought the issue was solved when I made my earlier post, but the fact is that I could not clean the gunk (or whatever it was) out of the chamber with Hoppes, a copper solvent, or even carburetor cleaner.
I subsequently purchased two more cleaning products: "Goof Off," which is formulated to remove latex paint, asphalt and tar; and Rust-Oleum Rust Stripper (which I specifically selected because it was acid based). Alternating between these two products, which I applied to Q-tips for the actual cleaning, I was able to clean out the coating.
If it was rust, I am thoroughly embarrassed. However, I'm not sure it was. I have used corrosive ammo before in other weapons, and I've never seen anything like this before. There was no sign of corrosion in the barrel or on the gas piston--it was all in the chamber, uniformly distributed, and stopped in a clean circle about 1/8 inch from the bore. It came out somewhat irregularly, with jagged edges to some areas, and it truly appeared that something had coated or been applied on the interior of the bore.
Due to weather issues, it will probably be a while before I can test the rifle out again. Rest assured, I will report further extraction issues, if I have any. Given the lack of information I was able to find on the internet on solving this issue (even though I came across enough items to suggest that this is not an entirely rare issue), I hope that this is of some help to someone.
(Update: I was able to test fire the rifle again a couple weeks later and it functioned reliably--I shot 90 rounds through the rifle without any problems. After returning from the range, I immediately cleaned the bore with both the ordinary cleaners and the "Goof Off").
Update (7/3/2015): Currently I have dropped back to simply using Windex (with ammonia) followed by ordinary gun cleaner/oil without further problems.