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Old 02-20-2012, 10:44   #27
Senior Member
Join Date: Dec 2005
Location: London
Posts: 6,085
I posted a clearly elucidated hypothesis explaining erratic ejection from Glocks a few months back which fits this fix very well.

In essence, the cartridge case does not have time to fall out of position. The slide moves about 1 inch before the case hits the ejector and it travels at about 1.5fps. That lasts about 0.125 seconds and that is not time to fall enough to matter, especially since the case is held by the chamber for most of that time.

More important is the fight between the friction between case and ejector and between case and extractor. If the friction at the extractor side is weak the case will tend to be pulled out from the extractor and will tend to pivot about the ejector rather than the extractor. Rather than its C of G being rotated forward and outward it rotates backward and outward, but the outward component reduces as the case rotates. This movement is limited because the case is blocked by and impacts the breechface. Without that impact, if it could get to 45 degrees, its momentum would be directly backwards.

In what we can consider as normal extraction, by the time the case has rotated 45 degrees its C of G is just about level with the port and if it is still constrained by the extractor its momentum will be taking it directly out of the port. As the slide is still moving backwards the case will be ejected further to the right than staight to the side. In the extreme of abnormal ejection where the rotation is entirely about the ejector tip the C of G of the case, backwards at 20 or 30 derees from straight out through the port ends up with the case bouncing around in the port rather than being ejected cleanly.

As the surface the ejector impacts is inconsistent, with some places rougher than others and some places with indented writing, the grip the ejector gets will be very variable. Bouncing around in the open port is variable in itself but when we add the variable initial conditions we get wide variation in the direction of ejection leading to stove pipes, double feeds and a scater of directions, including to the left, when the case does get thrown clear.

Many suggest wearing a hat and getting used to being hit on the head and I don't think they are intending to be humerous. In fact, any erratic ejection is a serious fault because it can put the pistol out of action when you need it most. Glock should have faced a class action well before now for selling a self defence pistol which does not meet the standards required for a self defence weapon.

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