

The mass of the bolt carrier, once in motion, wants to stay in motion and hits the bolt like a hammer, knocking it into rotation and into extraction. Almost all battle rifles, like the M14, M1 and AK use a delayed rotating bolt. There’s no “running start” to dislodge the bullet before turning the bolt. If the bolt is stuck to the inside of the chamber due to fouling (or crap ammo like in Vietnam) then there is often not enough energy to knock the bolt back into rotation. When the bolt carrier begins to move, it tries immediately to turn the bolt without first gaining momentum. There is no delay in the bolt moving during the extraction phase and this causes tremendous mechanical resistance.This becomes a monster issue if the bullet casing bulges during firing or if the chamber becomes excessively fouled, leading to failure to extract or half-extraction. And, the casing has to move a long way to disengage. The 5.56 has a relatively long, slightly tapered casing which begs for issues disengaging it from the chamber. The bullet itself is a reliability issue.Almost all infantry soldiers carry cleaning rods to clear this brutal malfunction so they can knock a spent casing out of the chamber and get back in the fight. This is particularly evident when the chamber gets fouled from use in combat conditions. This causes the extractor to want to slip off the rim of the casing causing failure to extract malfunctions. The extractor, due to its design has issues because it is similar to a teeter-totter that is out of balance.

This is one of the reasons the forward assist was developed. All can cause a bolt to seat incorrectly in the chamber, or not to extract after firing, causing a whole host of malfunctions. Any number of things can cause the lugs not to pass efficiently through the star portion of the chamber: dirt, heat expansion, ice, wobbly bolt carrier or wear and tear.
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The lugs on the bolt that lock into the star chamber are essentially a series of gears that if they don’t match up exactly, they cause a failure to feed or a failure to fire. Think about that for a minute: the point where the bolt, bullet, and barrel meet is almost impossible to keep clean in an AR-15. The single most important part of the rifle is nearly impossible to keep clean even in a garrison setting. The pinky never comes out clean and that should give us a clue.

They have two or three lug bolts and they are the gold standard for accuracy.Īsk any soldier about weapons inspection and they will tell you the test is worming a pinky in the chamber of the rifle. Bolt-action sniper rifles don’t have star chambers. Some say the star chamber provides accuracy. That’s the eight-petaled flower at the front of the bolt.
