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Old October 21, 2012, 12:31 AM   #7
Powderman
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Join Date: September 7, 2001
Location: Washington State
Posts: 2,160
Quote:
Honestly... there is no easy, one size fits all cure. BCG weight and mechanical resistance, magazines, gas pressure and recoil spring pressure... any and all can be contributors. I have many decades of AR "experiences", but I can't, with any easy certainty, diagnose your problem... only offer possibilities.
Actually, there is a solution...but it requires professional help.

A quick illustration:

We all are aware of how the timing in the AR series of rifles works. The cartridge is fired; powder burns as the bullet proceeds down the bore. As the bullet passes the gas port, gas starts down the tube, and heads back to the carrier key to enter the back of the carrier and start the unlocking process. Right about the time the gas gets to the carrier key, the bullet leaves the barrel. Just in the instant before the carrier unlocks, pressure has dropped to a safe level, and the rifle completes its cycle of operation.

Now, let's throw in the monkey wrench--the suppressor.

Same thing happens--the rifle fires, gas moves the bullet forward, the bullet passes the ejection port and the cycle of operation continues.

Here's the difference: In the regular rifle, the bullet leaves the muzzle and the gas escapes.

In the suppressed rifle, the gas is released--but then it encounters a new problem: The blast baffle, aka the first baffle in the suppressor. The bulet passes through, again greatly restricting the gas flow for a microsecond.

By this time, the gun is unlocking. The bullet continues its journey--but a large quantity is still in the suppressor. It HAS to go somewhere...but wait!

Another gas tube has opened up, while there is still pressure in the suppressor. That gas tube is the rifle bore--and gas goes roaring back down the barrel. The gas is still under a lot of pressure.

One indication is to look at the top of the disconnector. The hammer will slam it with so much force that a line of clean metal will be very visible. It will bend pins and break disconnectors if this continues.

Solution? There are two. One is to have a special barrel installed with a smaller gas port to decrease the gas flow.

Or, you can have an adjustable gas block installed.
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