This modification was invented and tested by my friend Oleg Datsenko.
Thanks to Sync for illustrations.

Remington 870 pump-action shotgun is simple and reliable. Simple construction of a shotgun is tested by time and by law enforcement and military members. This is very nice shotgun for hunting, home-defense and for police in close quarters combat.

But construction is not perfect for competitive shooting. There is no such thing as a perfect shotgun and all shotguns need tuning and enhancements for competitive shooting like matches of International Practical Shooting Confederation (United States Practical Shooting Association) or 3-Gun. Remington 870 as a shotgun for dynamic shooting has some disadvantages. Let’s take a closer look at a problem which competition shooters experience when they try to shoot multiple targets really fast.

This problem is no-feeds when cycling 870 as quickly as possible. When fired shell extracts normally but next round is not fed from the magazine tube. This is not a classic short stroke. Usually this problem appears on a shotgun with long magazine extension when shooter fires in high rate and tries to rack a shotgun fast. Competition shooters usually shoot really fast especially when they have groups of targets.

Solution of this problem will be interesting for competition shooters which experience “empty chamber” when they try to shoot fast.

This problem was experienced by me on a third year of my shooting career when I started to shoot with high speed. Two of my friends encountered the same problem. They are experienced shooters and that wasn’t a shortstroke. Also, I’ve heard about such “empty chamber” problem from other competition shooters.

Here is slow motion video which clearly shows that it’s not a shortstroke, because forend is pulled fully to the rear:

Round is still in a magazine tube.

So, let’s look closer how Remington 870 works. There are two latches, left and right, they feed rounds from the magazine tube.

Remington 870 Right Shell Latch

Remington 870 Right Shell Latch

Action bars have levers which open those shell latches, when forend slides forwards and backwards in needed moment.

Remington870, Action Bar

Remington870, Action Bar

Here is how shotgun works when you shoot at regular speed without sharp movements… When forend is in forward position, first round is held by left shell latch. After the shot, when you start moving forend backwards, right shell latch is on to stop the second round when first round lefts the magazine tube. Then, left shell latch is off, first round leaves magazine tube to the carrier, right shell latch catches the next round.

Shell Latch Holds Round, Remington 870

Shell Latch Holds Round, Remington 870

Right Shell Latch Holds Round, Remington 870

Right Shell Latch Holds Round, Remington 870

When you move forend forward, carrier lifts round and bolt pushes it to the chamber. In the beginning of this move, right shell latches switches of f and left shell switches on, the round jumps from the right to the left shell latch and held by left shell latch to the next cycle.

And this scheme works perfectly in normal rate of fire. But when you try to shoot faster, there is one problem. First of all, if you have long magazine tube, rounds depress magazine tube spring and move forward under recoil. Actually, rounds stay in place, but shotgun moves backwards under recoil. The most important is that rounds go forward from left shell latch to right shell latch. Right shell latch switches on when you start moving forend back. So when you rack forend fully backwards, round will be still blocked by the right latch and you will receive “empty chamber”. Next shot will be good because there will be no recoil and everything will work as it should.

The solution is simple but it requires gunsmith. You will need additional lever which switches off the right latch.

Latch Modification, Remington 870

Latch Modification, Remington 870

Latch Modification, Remington870 Shotgun

Latch Modification, Remington870 Shotgun

Now, this lever switches off right shell latch before left latch. And feeding works normally.

Here is video from one of the first tests of Remington 870 after modification:

Everything works perfectly.

One important thing to understand is that this mod is mostly required for competition shotguns with long magazine extensions.

Interesting thought about slug changeovers by Sync:
“The right shell latch cycles a second time later in the stroke, this mod may require some folks to alter their procedures for change-overs or emptying the chamber. They can’t just open the action slightly, set the next shell on the forward latch, and then open the action the rest of the way. If this mod is performed on an 870 with a long fore-end, changing or modifying the fore-end will probably be required to keep shells in the magazine while the action is opened. This helps to show why a typical 870 owner shouldn’t run out and have a gunsmith perform this mod on their HD or hunting shotgun.”

Here are illustrations which show how Remington 870 works with and without action bar modification. Also, they show normal operation of Remington 870 shotgun:

Remington 870 No-feed  Malfunction

Remington 870 No-feed Malfunction

Remington 870 Normal Operation

Remington 870 Normal Operation

Here is operation with Action Bar Modification:

Operation with Action Bar Modification

Operation with Action Bar Modification

Also, here is idea of Sync, he proposed this modification for faster shots and elimination of no-feed malfunction: “it’s simpler to machine, keeps the resistance in the slide movement more constant, makes change-overs a little less confusing, and should be less susceptible to wear”:

Action Bar Modification by Sync

Action Bar Modification by Sync

Have you ever experienced a no-feed malfunction on Remington 870?