non-mim extractor

[sb1010]

Would changing the extractor to a non-MIM have any chance of fixing shell ejection problems? My ejector looks worn on one side. I recently noticed a increase in fail to eject. By that I mean fail to eject the spent shell from the port. My express has had problems with fail to extract with certain shells. I solved the problem by avoiding those brands of shells.

[Synchronizor]

Is this only happening with a specific brand or type of shell? Different brands can have different rim shapes, and low-base shells tend to eject differently than high-base shells. Generally, due to simple physics, the 870 will eject shells more energetically if their center of mass is farther forward, which favors high-base and unfired shells over empty low-base shells (at least in a relative sense).

Also, weak ejection is often due in some part to the user being too timid with the slide. The best way to ensure reliable ejection - especially with lightweight low-base shells - is to rack the slide vigorously. You're not going to damage the gun by racking it hard; the 870 was an adaptation of the recoil-operated Remington 11-48 semi-automatic shotgun, so its action was designed to function that way. Even if you run it through the tens or hundreds of thousands of cycles needed to actually cause appreciable wear, the parts that take the impact when you slam the action open are easy and inexpensive to replace.

As for the extractor, the MIM extractors have virtually the same mechanical properties and relevant dimensions as the machined extractors. Unless yours is damaged or defective, it's probably not what's causing your problem. You mentioned that your ejector was showing wear, so I'd concentrate on that before the extractor. The ejector isn't normally a wear part, but if yours was damaged somehow, that could be related to your problem.

[sb1010]

I think I need to correct my original post. The extractor looks like it's showing wear not the ejector.

I was wondering if anything about the extractor could cause stovepipes and other failure to ejects.


Would changing the extractor to a non-MIM have any chance of fixing shell ejection problems? My ejector looks worn on one side. I recently noticed a increase in fail to eject. By that I mean fail to eject the spent shell from the port. My express has had problems with fail to extract with certain shells. I solved the problem by avoiding those brands of shells.

[Synchronizor]

I think I need to correct my original post. The extractor looks like it's showing wear not the ejector.

I was wondering if anything about the extractor could cause stovepipes and other failure to ejects.

Ah. Yes, a worn or damaged extractor can contribute to ejection problems. As the bolt moves rearward, the extractor holds the base of the shell against the bolt face until the other side of the shell catches on the ejector. As the bolt continues to move back, the relative motion of the ejector forces the shell to rotate about the point where the extractor holds the rim. Once the shell has rotated to the extent that it's pointing out of the ejection port, the rim slips from under the extractor and the the shell flips out and away with a little extra push from the ejector spring (in large-frame 870s). If the extractor is damaged or worn and is releasing the shell too early in this ejection process, the ejector will not always be able to impart enough momentum to ensure that the shell clears the ejection port. If this is what's happening with your 870, a replacement extractor should improve things.

A dirty or worn extractor spring or plunger can also contribute to function issues, so you may want to check them before you put in a parts order. Remove, inspect, and clean your extractor, extractor plunger, and extractor spring, and use a q-tip to clean any build-up out of their passages in the bolt. This video shows how to remove these parts and mentions cleaning. If the parts look good, put everything back together and see if the function has improved.

Would changing the extractor to a non-MIM have any chance of fixing shell ejection problems?

If your extractor is causing problems, it's because it's worn, damaged, or defective; not because it's a MIM (metal injection molded) part. A machined extractor, a MIM extractor, and a nickel-plated Marine extractor will all perform the same function. You'll have to decide what type you want, and are willing to pay for. This video gives a better view of the extractor replacement, and some brief information about the MIM vs. machined extractors.

[sb1010]

Could snap caps damage an extractor?

After a few times through the gun they seem to get some rough edges.

Also if cheap shells stick in the chamber?

[Synchronizor]

What kind of snap caps are you using? Most are made of softer materials than the steel extractor, so I wouldn't expect them to cause damage or excessive wear.

As for stuck shells, a major reason the crappy shells hang up in the chamber is that their steel bases aren't built strong enough to contain the interior pressure without permanently over-expanding. That soft and/or thin steel shouldn't cause excess wear to the harder, stronger extractor. Once, I had a high-base shell (an overloaded handload) wedge itself so solidly in the chamber that when I tried to use the ground-thump technique to clear the gun, the extractor tore completely through the steel shell rim. That shell was a lot stronger than any cheap target load, but my extractor (a MIM part) was unharmed. Once I knocked the shell out of the chamber with a cleaning rod, the gun continued to extract and eject just like it had before.

[sb1010]

I was using aluminum snap caps. I noticed they get rough after use.

[Synchronizor]

I use aluminum snap caps extensively. They do get chewed up with use, and I believe you can smooth them up with some sandpaper, but I've never bothered. I've yet to see them cause anything more than cosmetic damage, and the brass or steel bases on real shotshells will scrape off finishes over time as well. In an 870, virtually every part that a snap cap will come into contact with is steel (with the possible exception of the magazine follower), which should be much harder and stronger than any aluminum alloy one would realistically make snap caps from (probably a 6000-series alloy).

[sb1010]

Something I noticed when dry-firing. It seems like the shell coming from the magazine interferes with the shell that should be coming out the port.
I think shooting single shot I don't get the stovepipe.

[Synchronizor]

Something I noticed when dry-firing. It seems like the shell coming from the magazine interferes with the shell that should be coming out the port.

Does this only happen with snap caps?