Let me open this article with a comment for people new to building AKs – the best proven method is to use rivets. The Soviets did a lot of testing and the best mechanical join of the forged trunnions to sheet metal was a mechanical rivet. To this day, all commercial and military AKs are built using rivets. In my journeys, I have built AKs using welds, screws and rivets – all have pros and cons. What would I build an AK with that I care about? The answer is easy – rivets. This blog post documents my building a prototype using screws. Has it held up to casual non-military non-full-auto use? Yes. What would I recommend to you to build your AK? The answer is rivets.
In a previous post I described taking a milled stub and welding it to a sheet metal receiver. Another approach is to drill, tape and use alloy screws. So, let’s talk about that a bit. I did this build back in 2010 also. I actually still have the rifle and it’s one of my most reliable AKs. It takes about any ammo I stuff in it and I don’t recall ever having any issues.
For those of you who are wondering why I didn’t do rivets – I was bored and wanted to try something different plus this is a range gun and not something mission critical. Here we are 7 years later and it’s still doing fine – no cracks, no loose screws … but it isn’t stressed either. When in doubt, do rivets or a milled gun.
Also, bear in mind that the front trunnion was made from the milled receiver stub so screws made it real easy.
In terms of this build, I milled the trunnion down the same as I did for the weld build. I used my Hungarian AMD trunnion as an approximate guide for locating the holes and used two #10 screws for the front top and a 1/4″ for the rear. In both cases, I opted for national fine. 10-32 and 1/4-28. So, for 10-32, I used a #21 drill bit to make the hole and for the 1/4-28, I used a #3.
For drill locating and drilling the receiver holes, I used the AK-Builder trunnion rivet locating jig. You just put the trunnion on the jig, locate the hole, slide the receiver on and drill the hole.
Now for tapping, being square is a good idea. I squared my table to the drill press’s chuck and used it to hold the tap. I use Tap Magic cutting fluid to lubricate everything.
For the screws, I used alloy button heads and secured them with red thread locker. I reached in with a Dremel and ground down protruding screws.
So there’s the front. I used an air riveter to do the trigger guard.
End Result
Here’s a link to the AK-Builder Trunnion Hole Jig.
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