Mg2

[Gwhite]

The extractor tip geometry that seems to be required to work well is unlike any pistol extractor setup I've ever seen before. If my theory is right, it works by supporting the case at three locations instead of the usual two (extractor tip & rim pocket on slide face).

It's a bit difficult to explain well without drawings and pictures. The case is still in contact with the slide pocket on the left, but the extractor hits the case wall at the forward edge of the blunt tip in the photos.

4-1-22 Extr #2 +1 deg w Case (Clamped).jpg (45.42 KiB) Viewed 2242 times

That tips the case to the left, and the extractor slides down the case wall until the rim of the case hits the back of the extractor tip.

4-1-22 Extr #2 +1 deg w Case (Unclamped).jpg (45.07 KiB) Viewed 2242 times

The case is now held at three locations, but I think the key thing is that the contact at the back of the tip is a line and not just a point. The edge of the extractor is in contact with the front of the rim, which is (vaguely) flat. When the case is held this way, you can actually feel resistance to the mouth of the case tipping downward.

If your extractor is marginal in an MG2, you will typically experience jams after the 5th round. I think this is because there's nothing in the carrier to prevent the case mouth from sagging downward. That bounces off the slide rail, knocking the case loose prematurely.

The piece I haven't figured out is why nobody else's pistols require this 3-point support. It may have to do with the really fast cycling with the light slide. If the pistol pops up really fast in recoil, inertia will tend to hold the case mouth down.

In any event, those are my current theories... The extractor in the above photos shoots Aguila just fine now, and in several hundred rounds, hasn't bounced a case off the slide rail once.

[Ricardo]

Wow, you guys have done the rest of us a great service, doing all that experimentation! The slide weight issue makes sense to me (intuitively, which means nothing!). GWhite, the three extractors you show look a bit different to me in the lower photos. When you say you've adjusted the angle, do you mean the angle of the tiny bevel at the tip, or the interior angle (the "hook" so to speak)?

Your theory makes sense to me; most hangups do happen with the last round in my case; but not all by any means. I can't believe that this design is deliberate! Too finicky for the variation in ejector geometry.

I'm really encouraged by the findings of the both of you. Matchguns should be paying you for R&D consulting!

[Gwhite]

The "tip angle" refers to the angle of the blunt tip relative to the barrel axis. Unfortunately, it's hard to measure exactly. I have a tool grinder and a 3D printed extractor holder that I can use to adjust the angle in precise increments, but it's all referenced to the straight back edge of the extractor. I'm working on way to measure it photographically, but I'm not sure how well it will work. It appears that there is at least +/- a degree or two of margin, possibly more.

I've been working all along with the US importer, and I can't say enough good things about the support they have provided. Sometimes it can take a while to get them, but the factory has also been good about supplying parts. My long term goal is three fold:

1) Solve the pesky ejection issues that have plagued the EVO for a long time. I hope I'm getting close to that.

2) See if that will allow me to shorten the ejector to the point where it will permit clearing a loaded round without using the extractor lever. The pre-EVO's worked that way, and I don't see why the EVO can't as well.

3) Improve the longevity of the design. For example, the extractor has such a death grip on the cases that the cartridge rims are wearing a groove in the left side of my slide. I think that is why my first extractor stopped working. The groove got deep enough the extractor couldn't swing far enough to keep a reliable grip on all cases:

1088 Case Wear from Extractor Force.jpg (52.89 KiB) Viewed 2220 times

It's easy enough to stone down the extractor so it can swing in further, but at some point, that's not going to do it. I can at least slow down the wear with a weaker extractor spring, but I need to get the geometry figured out first.

[mmcyrus]

@Gwhite
I got quite same impression with mine MG2 from 2018 (just pre-Evo). I'm waiting for parts and then I'm going to try few things as well. Definitely I would like to try attaching tungsten weights to slow down slide. First, I need to figure out how to make it nice and tidy.

[Gwhite]

One issue that may come up if you add weights is cracked slides. The EVO's around the S/N 1050 - 1100 range had slides that tended to crack at the thin spot above the barrel hole. The original MG2's had a buffer in front of the center part of the frame where the barrel goes through, but they decided they weren't necessary. Kang Chua suggested using an O-ring, and I found one that would work as a buffer.

https://www.mcmaster.com/9558K21/

I installed one after many thousands of rounds, but my slide eventually cracked anyway. I installed one on my wife's pistol (1 serial number different), which hadn't been fired nearly as much, and her slide is still fine. I believe Kang is installing them in all the new EVO's. If you don't have one, they are cheap insurance.

[Dcforman]

GWhite, do you have a manufacturer/part number for that Oring?

Dave

[Gwhite]

Thanks to the auto formatting in the forum software, they stripped out the blank line I put in after it, so it's hard to see. There's a link to the McMaster Carr part # just above the picture. It's here: https://www.mcmaster.com/9558K21/

[Dcforman]

Oh geez. Whoops. Thanks!

Dave