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Getting to the Extraction Point...
Any operator will tell you that it's foolish to embark on a mission without a good plan for extraction once the objective has been accomplished. Similarly, it's foolish to design a firearm without serious consideration for the extractor, whose primary job is to remove the fired case before a fresh cartridge can be deployed. It's not an analogy we can take very far, but it does serve to illustrate the critical nature of this seemingly humble part. Just as the best rescue team may fail without a plan to get them out of harm's way, so a gun may fail without a well designed extractor.
The funny thing about cartridge extractors is that unlike, say, a highly trained air crew tasked with extracting a SpecOps team, a cartridge extractor is involved in nearly every phase of the mission. Cartridge extractors are necessarily located on one side of the bolt face--typically the outboard side--so that they can grasp the rim of the case and hold it securely until an ejector dislodges the case and flings it out of the action. In this position, the extractor, whether it wants to or not, also plays a role in feeding.
In order to perform its primary function, an extractor claw must reach inboard closer to the firing pin hole than the case rim's outer diameter. Naturally, this means that during feeding the case rim and the extractor claw will be vying for the same spot on the bolt face. One of them has to give way.
There are two basic types of extractors that offer two different approaches to this little "traffic incident."
1) The first type is a "push feed" arrangement. It might be more accurate to describe this as an "interference extractor" arrangement. In this arrangement, the extractor, with a spring forcing it inboard, temporarily displaces the case rim to the inboard side of the bolt face until the cartridge is forcefully aligned with the bore/bolt centerline near the end of the chambering process, finally pushing the extractor aside. Once the cartridge is fully chambered the extractor will snap over the case rim as the bolt goes into battery. This arrangement is generally quite reliable in its primary extraction role, but because it introduces some degree of cartridge misalignment during feeding, it can be problematic.
2) The second arrangement is referred to as "controlled round feed" (henceforth CRF). With this setup, the extractor and bolt face are designed in such a way as to allow the extractor claw to take its controlling position over the case rim as soon as the cartridge is delivered to the bolt face by whatever magazine feeding arrangement exists.
CRF has two advantages:
1) It mitigates cartridge misalignment with the chamber/bore/bolt face, and
2) by taking control of the case rim immediately, it eliminates play time for the cartridge making its way from magazine to chamber. Think of it as a bull being forced through a chute directly from pen to trailer. The bull has no choice. With push feed, there is the possibility, however small, that the bull may veer off course, because there is no chute, just a couple of cowboys with cattle prods.
This is not to suggest that push feed or "interference" arrangements are hopelessly inferior and unreliable. In fact, they are employed in the great majority of manual action rifles, and quite a few self loading rifles to boot. As we are aware, this works out fine 99.9% of the time.
There are a few rifle types that employ CRF, and it is my understanding that dangerous game hunters--if they choose a bolt action--insist on CRF bolts as insurance against feed failures in a life and death situation. The downsides to CRF are that such an arrangement typically requires careful tuning to function smoothly, and even with careful tuning, there is often a resultant small "hitch" in the feed process as the case rim moves into position inside the spring loaded extractor claw.
In contrast to rifles, the great majority of semi-auto pistols (I'm having trouble thinking of an exception) employ CRF by necessity. With pistols, there is a long jump--relative to the cartridge's short length--from magazine feed lips to chamber, both forward and up. Without the extractor's control, the pistol bullet would veer steeply upward as it left the magazine lips and hit the feed ramp, likely missing the chamber mouth altogether. The CRF extractor claw forces the case head against the slide breech face and into alignment with the chamber. However, as with CRF rifles, pistol extractors can require some careful tuning to work smoothly and reliably, particularly--but not limited to--older designs.
In fact in my experience, the number one cause of feed malfunctions in virtually all types of repeating arms is the extractor. That's how critical this little part is. But wait, there's more! Not only is the extractor responsible for a great many feed malfunctions, but also quite a few ejection malfunctions as well. How's that?
Well, most ejectors--the part which forces the empty brass to be flung out of the action--are pretty rudimentary devices, typically employing either a spring loaded plunger or some type of stationary bump stop. In any case, this simple device must push against the case head opposite the extractor claw, forcing the brass to pivot outward, with the claw as its fulcrum. If the claw fails to maintain case rim control long enough for the ejector to force the pivot, then brass may stay in the action, stovepipe, or in the best case scenario, just dribble out of the ejection port.
As you can see, the seemingly humble cartridge extractor is not so lowly a player. In the SpecOps mission scenario, the extractor is not just the air crew standing by to yank the rescue team out of hostile territory, it is also the mission coordinator. As such, it has more than one way to fail: too little involvement--mission fail; too much interference--mission fail; weakness in the face of adversity--mission fail; bad timing--mission fail. FAIL, FAIL FAIL.
There is only one way for the poor ******* to bring home a successful mission, and that is to do everything right, every single time, time and again, with no hope of promotion and very little hope of recognition. Heck of a job. At least you appreciate him now.
---------------------------------------------
RangerPointStore - M/94 Extractor Claws
Up next this weekend. We’ll be announcing the availability of our evolutionary new extractor design that finally addresses Marlin 1894 extractor-related feeding issues! Here's the previous discussion thread http://www.marlinowners.com/forum/ranger-point-precision/364274-here-last-evolution-1894-a.html
Adam
Any operator will tell you that it's foolish to embark on a mission without a good plan for extraction once the objective has been accomplished. Similarly, it's foolish to design a firearm without serious consideration for the extractor, whose primary job is to remove the fired case before a fresh cartridge can be deployed. It's not an analogy we can take very far, but it does serve to illustrate the critical nature of this seemingly humble part. Just as the best rescue team may fail without a plan to get them out of harm's way, so a gun may fail without a well designed extractor.
The funny thing about cartridge extractors is that unlike, say, a highly trained air crew tasked with extracting a SpecOps team, a cartridge extractor is involved in nearly every phase of the mission. Cartridge extractors are necessarily located on one side of the bolt face--typically the outboard side--so that they can grasp the rim of the case and hold it securely until an ejector dislodges the case and flings it out of the action. In this position, the extractor, whether it wants to or not, also plays a role in feeding.
In order to perform its primary function, an extractor claw must reach inboard closer to the firing pin hole than the case rim's outer diameter. Naturally, this means that during feeding the case rim and the extractor claw will be vying for the same spot on the bolt face. One of them has to give way.
There are two basic types of extractors that offer two different approaches to this little "traffic incident."
1) The first type is a "push feed" arrangement. It might be more accurate to describe this as an "interference extractor" arrangement. In this arrangement, the extractor, with a spring forcing it inboard, temporarily displaces the case rim to the inboard side of the bolt face until the cartridge is forcefully aligned with the bore/bolt centerline near the end of the chambering process, finally pushing the extractor aside. Once the cartridge is fully chambered the extractor will snap over the case rim as the bolt goes into battery. This arrangement is generally quite reliable in its primary extraction role, but because it introduces some degree of cartridge misalignment during feeding, it can be problematic.
2) The second arrangement is referred to as "controlled round feed" (henceforth CRF). With this setup, the extractor and bolt face are designed in such a way as to allow the extractor claw to take its controlling position over the case rim as soon as the cartridge is delivered to the bolt face by whatever magazine feeding arrangement exists.
CRF has two advantages:
1) It mitigates cartridge misalignment with the chamber/bore/bolt face, and
2) by taking control of the case rim immediately, it eliminates play time for the cartridge making its way from magazine to chamber. Think of it as a bull being forced through a chute directly from pen to trailer. The bull has no choice. With push feed, there is the possibility, however small, that the bull may veer off course, because there is no chute, just a couple of cowboys with cattle prods.
This is not to suggest that push feed or "interference" arrangements are hopelessly inferior and unreliable. In fact, they are employed in the great majority of manual action rifles, and quite a few self loading rifles to boot. As we are aware, this works out fine 99.9% of the time.
There are a few rifle types that employ CRF, and it is my understanding that dangerous game hunters--if they choose a bolt action--insist on CRF bolts as insurance against feed failures in a life and death situation. The downsides to CRF are that such an arrangement typically requires careful tuning to function smoothly, and even with careful tuning, there is often a resultant small "hitch" in the feed process as the case rim moves into position inside the spring loaded extractor claw.
In contrast to rifles, the great majority of semi-auto pistols (I'm having trouble thinking of an exception) employ CRF by necessity. With pistols, there is a long jump--relative to the cartridge's short length--from magazine feed lips to chamber, both forward and up. Without the extractor's control, the pistol bullet would veer steeply upward as it left the magazine lips and hit the feed ramp, likely missing the chamber mouth altogether. The CRF extractor claw forces the case head against the slide breech face and into alignment with the chamber. However, as with CRF rifles, pistol extractors can require some careful tuning to work smoothly and reliably, particularly--but not limited to--older designs.
In fact in my experience, the number one cause of feed malfunctions in virtually all types of repeating arms is the extractor. That's how critical this little part is. But wait, there's more! Not only is the extractor responsible for a great many feed malfunctions, but also quite a few ejection malfunctions as well. How's that?
Well, most ejectors--the part which forces the empty brass to be flung out of the action--are pretty rudimentary devices, typically employing either a spring loaded plunger or some type of stationary bump stop. In any case, this simple device must push against the case head opposite the extractor claw, forcing the brass to pivot outward, with the claw as its fulcrum. If the claw fails to maintain case rim control long enough for the ejector to force the pivot, then brass may stay in the action, stovepipe, or in the best case scenario, just dribble out of the ejection port.
As you can see, the seemingly humble cartridge extractor is not so lowly a player. In the SpecOps mission scenario, the extractor is not just the air crew standing by to yank the rescue team out of hostile territory, it is also the mission coordinator. As such, it has more than one way to fail: too little involvement--mission fail; too much interference--mission fail; weakness in the face of adversity--mission fail; bad timing--mission fail. FAIL, FAIL FAIL.
There is only one way for the poor ******* to bring home a successful mission, and that is to do everything right, every single time, time and again, with no hope of promotion and very little hope of recognition. Heck of a job. At least you appreciate him now.
---------------------------------------------
RangerPointStore - M/94 Extractor Claws
Up next this weekend. We’ll be announcing the availability of our evolutionary new extractor design that finally addresses Marlin 1894 extractor-related feeding issues! Here's the previous discussion thread http://www.marlinowners.com/forum/ranger-point-precision/364274-here-last-evolution-1894-a.html
Adam
