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GUNS Magazine March 2013 Digital Edition - Page 24
get out! extraction & ejection A Glen d. Zediker n “extractor” is there to pull a spent case out of the chamber and the “ejector” is there to toss it out the ejection port. When they don’t then they need fixing. Extractors first. Some seem to have decided that increasing the spring pressure or tension against the extractor is the solution to all problems. Nah. A whole lot of extraction problems have little to nothing to do with extractor function. I prefer to start with the simple view first. That’s the first step to solving a function problem. Right, make sure it’s plugged in before calling an electrician. Extraction problems come when the round doesn’t want to come out of the chamber, and they are augmented by cases sticking to the chamber walls, and roughness is a leading contributor to reluctance to release. A telltale sign is the extractor leaving its impression on the case rim, or even bending or tearing a chunk out of it. That means the extractor is trying just as hard as it should, but it’s tugging on an immovable object. The first thing then is to clean the chamber! If that’s not been a habit, then there may be residual roughness afoot. Usually this is plain old gunk, but under some circumstances there can be corrosion. Note that a culprit can be residue from a potentially corrosive-inducing bore cleaning solvent that’s leeched its way onto the chamber walls. Again, don’t neglect to swab and protect the chamber just as you would the barrel bore. All chambers in all rifles I own have polished chambers, bolt guns too. Shiny patches on spent cases are an indicator of sticking points in the chamber. Dirty chambers contribute to extraction ills, as will—not can—rough chamber walls. Glen polishes his. Clean a chamber with a nylon .357-caliber pistol brush (above), and then wrap it with a patch to finish. Below is an extractor spring Glen pulled from a new bolt. It had one of the phenolic inserts already in it. Middle is a “D-Fender” insert. This goes over the stock spring and increases tension about 400 percent. Inserts can be a fix, but not really a cure. On right is a chrome silicon spring from Superior Shooting Systems. It’s about a 100 percent increase compared to a stock spring. Do not run the CS spring with an insert or D-ring. Brownells has all. a problem, and abating this condition comes, most easily, from realizing that there’s too blasted much propellant in those cases. Additional (big) helps come from delaying bolt unlocking. As said, a case is supposed to swell up inside the chamber. Brass alloy expands and then contracts, and, since we’re talking about the firing process, all this is taking place in scant milliseconds. Delaying unlocking even a little bit, and along with it the employment of subsequent and sequential machinery that extracts the spent case, gives more time for the case to shrink from the chamber walls. Out she comes! A telltale on this problem is extraction with a normal-pressure load and not with higher-pressure loads. Other articles I’ve done have offered means to delay unlocking, but without gas system overhauls, adding some weight to the bolt carrier or running a stouter buffer spring, or both, work wonders. Let’s now say that none of those things are contributing to a rifle’s extraction problems, or, even if they are, there’s an absolute reason that a load has to function in the rifle. Now we can talk about extractor pressure. The extractor spring pushes the extractor in toward the bolt, holding it against the case. Extra spring tension makes the part grip more tightly and be less resistant to losing its hold. D-RING INSERTS There are gizmos designed to increase extractor tension. Specifically, these are the “D-ring” inserts that go in with the stock spring. They are made of phenolic (fancy plastic) material. They increase load, but too much. I think it’s a better trick to replace the stock spring with a better spring. I run chrome silicon extractor springs as a habit now. I can’t say I would have case removal problems without them, but I don’t have any problems. This spring material is unaffected by heat, doesn’t work harden, and doesn’t change function for a good 10 times longer than stock. It’s common enough for music wire springs to just break in full-autos. When a round is chambered, the extractor has to “snap” into place by sliding over the edge of the case rim. When there is more pressure to overcome due to excessive extractor spring resistance, there’s also more pressure put against the case head as the bolt is moving forward to lock down. This SIzING If you’re a handloader, as long as you used a full-length sizing die, case sizing really shouldn’t influence extraction. If there’s not been “enough” case body sizing, that usually creates feeding problems. The choice of brass might factor, though. The softer the brass alloy is, the more it swells and the “stickier” it gets. No semi-automatic should be run with 24 soft brass. Harder composition cases expand essentially the same amount but contract a little faster and a little more, and that’s the key. Brand names? Nosler, WW Commercial, Lake City with ’91 or newer on the head. The stronger the load the more the chamber contributes to extraction difficulties. When there’s an overage of propellant gas passing through the system, coupled with its symptomatic increased rapidity of bolt unlocking and rearward travel, what is really happening is that the case is still expanded against the chamber walls when the extractor tries to yank it out. If it’s trying to yank a still-expanded case, then a relatively rough chamber makes it more reluctant. Even in a mirror-finished chamber this can be W W W. G U N S M AG A Z I N E . C O M • M A R C H 2 0 1 3