Yes, There Is A Published Specification for the AKM Fire Control Group Pins

I had a fellow who was new to AK-47s/AKMs ask me the other day how the two pins work and if there was a published specification for them because his were floating in their holes. I learned a long time ago to try and help guys learn so I took a few photos and sent them to him.

Two Pins for Semi-Auto AKs

In a fully automatic AK, there are three pins and they are referred to collectively as the fire control group (FCG) pins – this includes the hammer pin, trigger pin, and sear pin – once in a while you’ll see the word “axis” thrown in there somewhere. For most civilians, we’ll just see semi-auto AKs so there are just two pins – one for the hammer and one for the trigger assembly which is made up of the trigger and disconnector. They are still called the FCG pins.

For anyone that is interested, a 1968 Soviet era armorer’s manual does have the pin specification:

This is from a Soviet era Armorer’s Guide that specs out the AKM fire control group pin. The shaft is 5mm and is where the trigger and hammer rotate. The same type of pin is used for both the trigger and the hammer – they are not unique.

Here is a pile of pins from a mix of countries. I had them in one of my parts boxes. The diameters of the shafts vary from 4.921 to 4.988mm according to my micrometer. Based on the armorer diagram above, a diameter under 4.97 or over 5.03mm is out of spec. Three of those pins were under 4.97 interestingly enough.

Odds are that the heat treat is messed up on his receiver or someone drilled the holes out of spec. He has enough info now to decide his next steps and since I wrote most of this already, I decided to post it in case it helps someone else.

Accessing the 1968 AKM Armorer’s Manual

I am going to try hosting his huge armorer’s manual PDF file and see how it goes. If people have problems downloading it, I’ll just remove the link – click here for the 64MB PDF file. Note, I am not the owner or creator of that file. Someone did us a huge favor by taking the time to scan in all the pages and share it. It is in Russian and has a ton of diagrams.

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