I love my AK-47, I know AR-15’s are more popular here in the states at the moment, but trust me these are fun guns to own. I’m posting this to help share some knowledge I have learned over the years. If you decide to pick one up here are a few things to look for. If I note something incorrectly I encourage you to correct me.
First, while not a deal breaker just a sign of reliability and good construction, look for the letter “G” stamped into the front trunnion. From what I have gathered this is a mark synonymous with a barrel that was press fit into this trunnion and then imported into the United States. I believe imported from the Romania/Ukraine region of the world if memory serves.
THE TOP COVER
Second, this is more applicable when looking at a used firearm, is to look at the top cover. The front of the top cover should be under a portion of the front trunnion and stay on when you give it a little tug backwards. If the cover comes off without depressing the spring loaded button protruding from the rear of the cover, walk away… unless you want a little project. More on the reason for this in just a moment… Also, look to see if the rear of the cover has had any spacer material welded or glued to it or the rear trunnion itself. Again, if so walk away.
Third, look at the front and rear trunnion rivets best you can. What you will find is that the rivets/trunnions were not installed properly. Often with imported steel, the rivets were simply made of sub-par material, meaning they are too soft. Because of my background as a mechanical engineer, I have seen the effects of poor quality steel first hand. Unfortunately, you will not be able to tell the quality of your rivets by simply looking at them. So there are two aspects of the rivets to look for, though difficult to detect by simply looking at the assembled firearm.
The first thing is to see if the lower receiver was coined into the trunnion countersinks present at each rivet hole. Look for a subtle bend or radius around the rivet denoting that it was bent down into the countersink.
The second thing is to ensure that the rivets were coined into this countersink pocket and not just a flat underside sitting on the receiver. Illustrated below, you will better see the reasons for why this is so important. The recoil from firing the firearm will, over time, shear the rivets. The first sign that this is happening is the top cover will start to come off as the front and/or rear trunnions move further apart as the rivets shear.
If this has started to happen for you there is a solution, but it involves some effort to rectify. The trunnion rivets that have begun to shear will need removed. This often involves a small grinder tool to remove a head or both heads of the rivets. Then forcing the rivet body out of the hole. Ensure that the receiver (or frame) is properly coined into the trunnion countersinks before installing the new rivets. If the receiver is not coined into the countersinks, I would recommend that you do so.
Purchase good rivets from a reputable supplier, this is a common problem so entire rivet kits are readily available. (www.k-var.com) To reinstall the rivets, riveting tools are often offered by the same supplier replacement rivets are found. There are several ways to accomplish reinstalling the rivets, just make sure you don’t damage the firearm in the process. Be sure to coin the rivet down into the countersink.
I hope this has helped someone out there, and again I am not an expert, just sharing my experience. If you have any input on this subject I’d love to hear it. Thanks for reading.