Rather than beat a dead horse, I thought I'd try to describe this infamous extractor, and others of Remington's competitors, the differences, the pros and cons. And there are both in all designs.
My Remington info comes directly from the excellent book by John Lacy The Remington 700....25 years (1962 through 1987). I don't have an M700 here to measure and fondle but have had several of them in my hands over the past four decades. There have been many small changes in the M700 over the years and the extractor was changed several times.
The Remington extractor was used on models 722, 721, 725, 700, (ADL, BDL, CDL etc,) and the 40 X series of rifles as well as the USMC M40.
The Mike Walker design was genius. Genius in that it met the criteria set forth by the management of Remington and it was a rifle that could be produced and sold at a profit when times were hard in America. It cost more to manufacture the pre 64 Winchester than two new Remingoton M721s cost retail.
It was also a genius departure from a half century of bolt action design that was considered to be the best bolt action ever, the Mauser 98. One of the design strengths was the fully enclosed bolt nose, encased in the barrel extension or flange which is screwed into the receiver. Three rings of steel. Bolt nose, barrel and receiver ring. Solid, enclosed like a vault. The strongest and tightest gas seal of any bolt rifle, no argument there. It does require no cuts in the bolt nose for the extractor or the three rings will be violated. Now, where can we put an extractor? That was genius! Seriously. To come up with such a simple extractor without violating the vault like integrity of the three rings. Actually it was an enlarged and beefed up extractor from a popular 22 rimfire rifle made at the time.
The extractor of the M700 was the extractor of the M721 which evolved into the M700. After the first year or during the first year of production the extractor was changed. This was to enlarge the gripping area of the extractor to get a better bite on the case rim. It made the biting surfaced curved and wider, the previous was straight and grabbed a much smaller area of the case rim. At this time the extractor was riveted into the nose of the bolt at one end. It rides in a channel slot milled inside the extended nose of the bolt. This slot in the early guns (riveted) was a horse shoe shape eccentric to the diameter of the inside of the bolt nose.
In 1974 a change was made to eliminate the rivet.
An interesting observation is made here. The Extractor was said by Lacy to work fine but was modified by eliminating the rivet to facilitate easy change out of the extractor....[ that worked so well.] (??) Why change out what worked so well. Anyway, I digress.
When the rivet was eliminated, the slot milled inside the bolt nose was changed. The horse shoe shape was enlarged and two semi-circular slots were milled at each end for the extractor. The extractor was also changed to fit this new slot with a wider curl at each end to hold it in place. At one end the semi-circular slot was left with a "bump" to stop the end of the extractor from working around and getting out of place.
This is the decade and a half when I owned Remington rifles. From the mid 1970s to about 1990. This rivet-less extractor worked very well in most M700 but in some it did not. I think I owned all those in which it did not work so well. I have owned and fired over 100 Remington M700 rifles. I also sold many of them in my shop for a decade. They have many very satisfied owners.
Lacy states he has owned/handled hundreds of M700s and only found one ejector fail and it was a defective from the factory. (Wouldn't snap over a round.) I too have owned only one M700 that came with a defective extractor. A post 1983 riveted (more on that later) 416 Remington mag. I have however had many fail after shooting the rifle.
In 1983 Remington engineers decided the rivet-less extractor, with its larger milled slot in the nose and the .532" diameter cut for the magnum caliber, did not have enough steel in the inner ring of steel (the bolt nose) so they went back to the riveted extractor and smaller cut for belted magnums. (This was my 416 extractor) This apparently proved more reliable for most magnum M700 rifles but the one that didn't work....ever regardless of how many times it was fixed, my 416. I also had a 7 mag that shot like a house a blaze but would only take about 40 rounds before extra cleaning was needed to get brass chips out of the extractor cut.
What is a failure of any extractor?
Failure to pull the empty fired case or loaded round (we do unload our rifles sometimes) out of the chamber. Also there is some combination of extraction and ejection functionality to make for smooth and successful cycling of empty out live round in that can be a failure of either component, extractor or ejector.
Lacy states that the rim of some military brass can, in some cases, damage the extractors....[ and cause them to fail to I presume]. I can tell you that after about 300 to 400 rounds of LC match 7.62x51 ammo through my wonderful 40X, it did fail to extract about one out of three. They were relatively easy to change back then and I kept several on hand. But the truth is that after about 500 to 600 rounds of any ammo this same gun/extractor failed to extract. I shot the rifle over the NRA course for a while then shot steel with it, then shot coyotes, deer, wild pigs.....
Also one of the failures I have experienced with some guns was the brass chips from the cartridge brass (I mostly used Remington back then) would get under the extractor in the milled groove in the bolt nose and hold it out away from its slot. This would keep the extractor from snapping over a round. This usually starts as a tight to close bolt then it wont close at all. Anyone ever see a brush designed to clean this out of a M700 extractor?
Is the Remington extractor more likely to fail than other extractors?
Honestly I don't think I've shot but one other brand of rifle as many rounds as I've shot through each of four different Remingtons. I have shot two Sako A series rifles as much as any Remington. I still have both and no parts have been replaced and I have never had a fail to extract or eject form either. I have owned more than 300 Sako rifles since 1972.
I've had many failures to feed, eject, extract from many rifles, some because of the action not designed/built to fit the cartridge I was trying to fit in the gun but there have been many failures. Point being, I do not think for the average hunter/rifleman that a Remington M700 is more prone to fail in daily use. I don't think it is as durable as some other designs and when the limits of the extractor is reached, it requires replacement and it is not an easy job in the field. I will say that the M700 extraction system, with the plunger and spring ejector is not as durable as other types. Durable as in its ability to take use or abuse.
Lacy also states that gas leaks or catastrophic failure [of the cartridge case] can damage the extractor. I will certainly agree. Also excessive pressure rounds that tend to expand the case head/rim will also damage the extractor. Such was the case (pun intended) with my 300 Weatherby M700 classic with accidental CDL stock. Beautiful......took about 30 rounds to do it the first time. Wouldn't extract!
I have hand loaded about one million rounds of ammo. I've shot most of it. I have on occasion loaded ammo above the SAAMI specifications for the particular caliber. This has in some brands of guns caused problems. It has caused no operational problems in my Sako rifles and I have probably inadvertently overloaded them more than others since they have been my test bed for so long. I have overloaded and seen several M700/721s fired with loads that exceeded pressure limits. I've also seen the M700 series of guns stay together with the only visible damage being to the extractor. This has led some to think the extractor failed. It did fail but with loads well beyond the norm in pressures and this constitutes a failure in the shooter/loader rather than the rifle. I epoxied a strain gauge onto one M700 rifle and three different Sako rifles to test pressure readings with the Oehler M43 system. I can tell you, you don't want to shoot the loads that will damage an M700 extractor.
The Sako extractor is used on all Sakos since 1972 and is used presently today on the new model 85. My extensive testing has been with the two lug bolts of the model AII, AIII, AIV, AV actioned rifles.
The Sako extractor it is actually an adaptation of an extractor designed by Paul Mauser and abandoned for the more robust design of the M98 claw extractor. It is a simple device installed in the bolt nose, which looks much like the Remington bolt before the extractor cut. The bolt has an extended flange or nose of about .120" enclosing the case rim. The extractor is at the same diameter as the bolt, not recessed. The extractor is about .250" in width and the length of the locking lugs at about .500". It is extremely simple device to change. I've only had them out to clean out behind them. I have two spares I bought back in the 1980's and have never replaced even one extractor.
The front receiver ring on the Sako is longer than the Remington and thicker. When the bolt is pushed in it push feeds a cartridge ahead just as the Remington does but .500" into the ring is the bolt lug raceway. The nose of the bolt is engaged into the ring the full length of the locking lugs then the extractor is allowed to flip up and over the cartridge rim while it is enclosed in the raceway. No slack is needed in the extractor cut or the receiver ring to allow the extractor to snap over.
The extractor is also positioned along the diameter of the bolt to rotate it behind the lower lug raceway when the bolt is locked. About 2/3 of the width of the extractor is behind the lower receiver lug when the bolt is fully closed. This insures that the extractor cannot slip over a cartridge rim when the bolt is rotated up during extraction. The caming action of the bolt lugs in the raceway will pull even a stuck case from the chamber. I have beat locked bolts open with a rubber mallet (don't try this at home), many times and the Sakos always brought the case with it. I have never created a failure of this extraction system with all the abuse I've heaped on this design. In fact I've yet to break a Sako rifle.
I'm sure this will raise questions so I'll wait awhile.