I had some trouble with hammer follow using NDS-3 receivers and Tapco G2 fire control groups. I contacted TAPCO. They said they hadn't heard of it happening. I contacted NoDak Spud. Harlan recommended I buy the arsenal 1-claw group. I bought the arsenal. They worked better, but could still get some occasional hammer follow. I designed a fix for the Arsenal 1 claw (reduce hammer height .010-.020").

Since the Arsenal are significantly more expensive than the TAPCO, especially when we are buying 200 at a time, I decided to analyze the issue methodically to determine a way to adjust the G2 to work reliably, safely, and consistently in the NDS3..

In some circumstances, with some NDS receivers and some TAPCO G2 trigger groups, with the trigger pulled in a certain way, the hammer can follow. Its a stacking of tolerance tied to the receiver rail height, the bolt carrier base, the hammer-trigger hole spacing and height relative to each other and to the rails (and therefore the bolt carrier).

An examination of import fire control groups will show some with signs of adjustment on the engagement surfaces. This is because factory AK trigger groups are hand-fitted and numbered to the gun. They are not always interchangeable between guns.

Just as relevant as receiver and trigger group dimensions is how the operator manipulates the trigger. A solid, fast pull to the rear will rarely get a hammer follow. A slow, smooth pull and holding at the point of hammer release may get a follow.

I've spent most of the last month analyzing this phenomenon using around 30 different rifles. I recorded the dimensions from the different hammer, trigger, disconnector & receiver sets, and correlated them to whether or not I could initiate a hammer-follow. I analyzed the dimension tables to determine the optimal degree of adjustment.

• I identified the potential problems.
• I determined the possible causes and probability of occurrence
• I determined the adjustments necessary
• I quantified the degree of adjustment
• I proofed my results on 50 rifles.
• I forwarded the data to Nodak Spud and TAPCO for their reference.

The results I obtained are dependent on the slot cut for the 2nd arm of the 2-claw trigger being 4.25mm. This is shorter than the Left side cut side cut. If the cut is too long, the trigger can rotate too far forward. The rotating hammer may then hit the TOP of the disconnector, rather than the camming surface on its leading edge. result is disconnector failure (hammer follow). If the cut is too short, the trigger does not travel far enough to release the hammer. While other lengths will work, 4.25mm is the constant I used to isolate the hammer to disconnector dimensions.

PROBLEM. The hammer does not rotate downward far enough for the disconnector to catch.

SOLUTION Lower disconnector shelf on hammer and/or raise disconnector claw height .

DETAILS I lower the disconnector shelf by .030"-.035". I raise the disconnector claw height by .005" to .010" (total of both .040"). I lightly polish the sharp edges. Since I am machining the mold lines off and polishing the surfaces anyway, this doesn't add much time to the assembly.

PROBLEM The modified hammer is now shorter in shelf height. (usually around .410") The disconnector does not cam forward far enough for secure engagement.

SOLUTION Increase disconnector engagement.

DETAILS Cut off the front tab of the disconnector leaving .250" from inside front of hole to end of front tab. Assemble to trigger with sleeve and spring. Measure distance between trigger claws and disconnector claw (I use a pin gauge). remove material from front underside of disconnector a little at a time until the gap on the assembled unit closes to 15% smaller than the hammer shelf width. This is usually around .350" (.350 = 14.6% less .410"). Test with trigger at rest. rotate hammer rearward. hammer must pass disconnector in both directions without touching, but with gap as close to 0 as possible.

PROBLEM Disconnector does not release hammer, or disconnector releases hammer but still contacts when hammer passes.

SOLUTION Decrease disconnector engagement

DETAILS Using the 85% guide, the disconnector gap ranged from the slightest contact to .005". If disconnector touches hammer, polish rear of hammer and/or front of disconnector. The lateral play in the hammer makes this dimension hard to measure.

PROBLEM Ttrigger won't return forward without assistance.

SOLUTION Adjust angle of disconnector relative to hammer shelf.

DETAILS The disconnector claw is too sharp. it is pointing downward like hawk's beak relative to the hammer shelf. Polish the hammer shelf. put a slight bevel (.020") on the edge. Polish the front of the disconnector claw (the hooked beak part) Put a slight bevel (.020" on the disconnector claw front edge.

All 30 guns yielded a disconnector gap ranging from slight contact to .008" Most were 0 to .005". a few needed the hammer shelf radiused slightly - the disconnector didn't stop the hammer from releasing but there was slight rubbing. I have complete 60 rifles and cannot coax any of them to hammer follow. I understand that this is a small statistical sampling. I will update my results if further data collection suggests a different adjustment process.