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AK47 Feed System Secrets

1583 Views 4 Replies 4 Participants Last post by  Clint
I was thinking about the bottom 6Oclock lug on the AK bolt and trying to figure out if there was anything special about the feed system.
I have a few questions that one of my brothers with an AK laying around could answer.

When you insert a full mag with the bolt closed, is the cartridge stack depressed by the bottom of the bolt carrier?
Any difference in insertion force required if the bolt is held back during insertion?

Does the bolt carrier drag/touch the top cartridge during its initial rearward movement or is it only the bottom lug that interacts with the cartridge stack?


Cool picture here.
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Thanks guys. I just google all these pictures.
This semi confirms part of my theory about one of the AK's reliability secrets.

It's funny, Everybody "knows" the AK is reliable, but very few people actually know WHY

Anyhow, the theory goes like this...

Each phase of the loading cycle occurs in a separate portion of the bolt carrier's travel, with no overlap between phases.
This way, any variations in the forces required/used for any particular phase are taken separately and not added together.
This prevents resistances from building up to high enough levels to stop the cycle.

Some details ( distances are approximate )
-the first 1/4" of rearward travel is for accelerating the bolt carrier up to speed only. No feedstack drag, no cam track work, no extraction, no hammer movement.
-the next 1/4" is for rotating and unlocking the bolt. No feedstack drag, only cam track work and initial shell rotation.
Since the bolt carrier is already up to speed, there is an impact wrench/slide hammer effect available to help break loose the stickiest of cases.
Anyone that has shot too hot handloads through a bolt action knows that it may take considerable force to lift the handle.
The hammer is contacted roughly halfway through the bolt rotation.
- the next 1/2" is for partial extraction of the case. The impact effect is available here too.
At the endpoint of this phase, ( 1" in total travel ) the piston vents pressure and only the inertia of the bolt carrier is available, but the hard work is done.
- the next 1.5" is where the 6 O clock lug drags across the top the feedstack. The spent case is already loose and does not provide much resistance as it is fully extracted.
The hammer is recocked during this travel and is fully complete before the case hits the solid ejector at the end of this phase.
- the next 2" is where the bolt carrier moves fully rearward and slows, hitting the rear trunion.
Notice the bolt face moves at least 2" behind the next case. This leaves plenty of time for the next case to pop up and settle into the feed lips, practically eliminating any short stroking issues.

compare this to the (abbreviated because we're all familiar) AR operation.
The bolt carrier must accelerate while rotating and unlocking the bolt, while dragging across the feedstack and recocking the hammer too.
Next, the case extraction and hammer recocking occurs while the bolt lugs drag across the feedstack too.
Luckily, there is an impact effect available to help extraction as the cam pin gets to the end of the track.
The case is ejected and the bolt face moves only slightly past the bolt stop.

That's enough for tonight, I see smoke, so I'll do the return cycle tomorrow. 8)
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