Trigger slap is a minor, yet common problem shooters of the AKM pattern rifle may experience. This post will get into detail about what trigger slap is, and the specific point during cycling that it happens. I've also provided instructions on how to fix it, as well as discussing a few myths circulating online about trigger slap.
What Causes Trigger Slap on the AK47?
Trigger slap happens during cycling of the AKM rifle, specifically when the disconnector and hammer don't engage properly. Here is a breakdown of the function, you can click on the thumbnails below to pull up a larger technical drawing of each phase.
When does trigger slap happen during cycling?
Phase 3 is when trigger slap happens. Two things can cause trigger slap. In the first case, trigger slap is caused when the disconnector cannot move backward far enough to clear the hammer. In the more common case, the disconnector moves too far (over travel) and impacts the trigger, forcing the trigger to rotate. In either case, this force is translated through trigger where it snaps the shooters finger, causing discomfort.
If the disconnector is not able to properly move through its range of motion, the trigger will slap. Lets take a look at some animations of proper disconnector function, and another causing trigger slap.
Correct Disconnector Function
Here is how a properly functioning disconnector looks during cycling. Note how the disconnector is able to move freely and independently of the trigger as the hammer is cocked.
Disconnector Causing Trigger Slap
Here is how a malfunctioning disconnector looks, note how the hammer is forced to rotate the trigger forward in order to clear the disconnector.
Note how the disconnector bottoms out and impacts the back of the trigger, forcing the trigger forward. Take a closer look at the freeze frame of that phase:
Now that we've identified the cause, lets talk about how to fix trigger slap.
Fixing AK47 Trigger Slap
When the disconnector is causing trigger slap, material can be removed until it has enough room to move freely.
Using a file, the area identified can be removed until the disconnector functions properly. Removing material will allow the disconnector enough room to move rearward freely, without impacting the trigger.
Begin by removing a small amount of material and checking the function, repeat the process until the trigger slap is eliminated. With the rifle unloaded and the dust cover off, a functions check done by hand can determine if the disconnector and trigger are engaging properly. Once the trigger slap seems to be eliminated, take the rifle to be fired at the range to confirm the disconnector is moving properly.
Things that Don't Cause Trigger Slap
There are two common myths floating around online about the causes of trigger slap. Neither one is entirely true.
Trigger Slap is Caused by the Disconnector Tail
The Myth: The tail on the disconnector causes the trigger slap.
The Truth: A disconnector with a tail is from a full auto fire control group. When in the full auto firing position, the selector lever blocks the disconnector from catching the hammer by pressing down on the tail. Its not needed for semi-auto only guns and doesn't have anything to do with trigger slap.
Trigger Slap Can Be Prevented By A Special Trigger Guard Rivet
The Myth: The Bulgarians created a special trigger guard rivet for the disconnector to rest on, subsequently preventing trigger slap.
The Truth: The jury is still out on this one. The enlarged flat headed rivet used by the Bulgarians does seem to prevent overtravel of the disconnector and trigger slap.
However, this introduces an extra and unnecessary part (see Rube Goldberg machines) into the system. We know the proper fix for trigger slap is to make sure the disconnector is properly sized so it doesn't impact the trigger during the cocking phase.
Further, it results in the disconnector tail smacking the rivet, which leads to peening of the rivet. With enough material peened it could eventually lead to the trigger slapping again, but it would likely take an extra ordinarily high round count to see this manifest.
From an engineering perspective, a better fix for trigger slap would have been for the Bulgarians to have removed material from the bottom of the disconnector (as shown above) rather than develop and introduce a new part into the system. Also, for those shooters who are using a semi-auto style disconnector, changing the trigger guard rivet wont solve the problem. The semi-auto disconnector doesn't have a tail and can't touch the rivet.
The most proper solution is not a special rivet, but rather is to remove material from the underside of the disconnector until the trigger slap is eliminated.
We've pin pointed the specific cause of trigger slap in the AK47 by identifying the specific point in time that it happens, and what can be done to fix it.
Trigger slap is a frustrating problem that can take the enjoyment out of shooting. Fortunately, its a simple fix that can easily be done in a few minutes with a hand file. Hopefully this guide has been helpful, happy shooting!