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Posted: 9/18/2010 1:04:09 PM EDT
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I know most of the .22 conversions don't extract live rounds very well. I never really thought about it until today when I was messing around with a build. So, now I am curious why they extract fired rounds, but don't extract live rounds. Also, how did CMMG change it so their new ones do extract live rounds?
Here is what I think: When the bolt goes forward, strips a round and feeds it, the rim of the cartridge is up against the chamber/barrel and the extractor can't grab it. When the round is fired the case moves back, seating or locking on the extractor, then is continued to be pulled to the rear by the bolt until it hits the ejector and spins out the port. Is that it? Or is it something else? Can live round extraction be improved? |
| Many .22 short pistols have no extractor. The bolt doesn't "pull" the case out; motive force is provided by the case, which functions as a piston, kicking the bolt back. The extractor mainly functions as a fulcrum for the case to pivot on when kicked by the extractor. |
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I'm just trying to understand both: live round extraction vs. extraction when being fired.
So, under fire, the case basically extracts itself as a result of being blown back, hits the ejector and spins out of the upper? Live extraction is based on the extractor's ability to grab the rim. This is done by the extractor slot allowing the extractor enough room to grab the case rim? Here is what I'm asking for. On the barrel on the left the extractor cut doesn't quite meet the bore. It won't extract a live round (when I say live, I'm using dummies, but it doesn't matter for this purpose). The Ceiner adapter on the right has a deeper cut. So does my Tac Sol dedicated upper and M261 conversion. They extract live rounds pretty good. Could live extraction on the left barrel be improved by deepening the extractor cut, but not penetrating into the bore? 
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Yes, but too thin risks blowouts. I have seen a pretty expensive 10/22 barrel on which this happened.
On fired rounds, the extractor is just there to help keep the case properly located on the boltface so the ejector can, as you properly describe, tip/spin the empty out. Sharpening/recontouring the hook on an extractor can help live round extraction. Somebody (Volquartsen?) advertises a concave extractor groove to improve live round extraction. There are frequent reports of 10/22 owners noticing missing extractors on guns that run fine. Obviously, they can't extract a live round. |
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