Short shells in 870

[shawnm]

I put a +2 on my 18" 870 for a magazine capacity of 6. My 20" 590 has a magazine capacity of 8. This is a bit frustrating and I guess comes down to the spring. I really feel like I should be able to get 7 2.75" shells in there. The 7th shell comes very close to fitting and I'm thinking of grabbing a box of 2" Aguilas to test and if they run reliably, use as a topper-offer.

Anyone play around with these short shells in an 870?

[Synchronizor]

What extension did you install? Some +2 extensions aren't very space-efficient due to poor or cost-optimized design, others intentionally give up some space for reliability. Springs can make a difference, but they're only one variable, and usually not a major one. The S&J Hardware +2 extension is one I've tried that makes good use of its space; it'll fit under an 18.5" barrel while acting as a +3 with many 2.75" shells that have typical crimped lengths. It's not a particularly cheap option though, you pay for what you get.

The 870 - and most shotguns for that matter - isn't completely reliable with the Aguila mini-shells. A major issue is that as they're pushed out of the magazine, those stumpy shells can bounce around in the receiver and wind up in an orientation that prevents them from feeding into the chamber. They can also be iffy about ejection. See this video for examples of malfunctions in an 870 and an Ithaca 37. Working the action at a certain speed, or with the gun in a certain orientation, can improve reliability somewhat, but not enough that you'd want to trust them for critical applications like defense.

Cabelas sells a 2 1/4" 6-pellet 00B shell that I've found to be reliable in my 870. It won't improve capacity as much as the 1 3/4" Aguila shells (which also have shorter fold crimps compared to the shallower roll crimps on the 2 1/4" load), but it's good for one more shot in a lot of tube magazines. Extremely low recoil, too.

[shawnm]

Thanks for the reply! The extension is a one-piece +2 from Scattergun Technologies. It came with a new spring and follower. The follower (as I'm sure you know) takes up more space than the stock one which is hollow and the spring is very strong, much stronger than in my 8+1 590A1. I clipped a few coils off the spring and switched back to the stock follower and was able to get all but about 0.3" of a 7th shell into the tube.

I haven't examined the Mossberg spring but I've seen in videos that it appears to be tapered and I'm thinking that's so that it will compress into less space.

I'll check out those 2.25" shells from Cabela's. I was thinking I'd load just one short shell first in and then run standard 2.75" for the other 6 - kind of like a last resort kind of thing. I'll also check out the S&J though I don't really want to buy another extension since I just got this one.

[Synchronizor]

The Wilson Combat/Scattergun extensions are good kits, reliable and an excellent value for the money. But because they're a budget kit, they're made to a price point, so you get things like a non-relieved end cap that saves the company machining steps:

Wilson Combat end cap.png (86.93 KiB) Viewed 15905 times

Also, the Wilson Combat +2 is sized to fit under a true 18" barrel, not the 18.5" barrels that are more common on current fighting 870s.

The spring in the Wilson Combat +2 kit is a beehive spring, wider in the middle and narrower on the ends. This and a relatively slim wire diameter makes it pretty space-efficient. It's plenty stiff for good function, especially if you're not machine-gunning your 870 with heavy loads, so you can trim a little off. Just don't get too carried away, especially if the spring is relatively new, and hasn't taken it's initial set yet.

Cup-style followers take up less space than tailed followers, but then you need a narrow spring that can fit inside the cup, and a narrower spring tends to have a longer solid length. Tailed followers work well with wider beehive springs, which have fairly short solid lengths. In my experience, it's generally 6 of one, a half-dozen of the other, but you can sometimes find combos that get you a little extra space for shells. Just be sure to test that combo thoroughly for function as well as capacity; I would take 6 reliable shells over 7 iffy ones any day of the week.

Another thing to look at is the shells. You may not need to go with special shorty shells if you're as close to that seventh shell as you say. Even if shells have the same unfolded lengths, their crimped lengths can and do vary. Some shells like fold-crimped Estate buckshot tend to be shorter than average, while others like Federal Flite-Control buckshot tend to be a hair longer. Even less than a tenth-inch in crimped length per shell can make a significant difference once you multiply it by 6 or 7.

But let's put aside all that hair-splitting with the mag tube for a second. If you're really worried about running your gun dry, you might get more benefit from installing a sidesaddle or butt-cuff to hold extra shells, and practicing topping the gun off as you shoot. Just slipping another shell into the magazine after you first pick the gun up & chamber a round is a free +1 that only takes a second.

[shawnm]

Yep! I've got Esstac on velcro on both guns. That's a great point about different ammo manufacturers. My buddy and I are thinking about getting into shell reloading in which case I imagine it would be trivially easy to get setup to get that 7th round in the tube.

[shawnm]

So big picture, how is it that the 20" Mossberg 590A1 gets a 8+1 capacity when an 18.5" 870 "only" gets 6+1 with a similar relative-length magazine tube?

If I didn't have the Mossberg it probably wouldn't bother me so much but it's confounding that the Mossberg fits 2 more shells in an extra 1.5" of space!

[Synchronizor]

Fold-crimped 12ga 2.75" shells are usually 2.3" - 2.4" in their unfired state. Sometimes a bit more, sometimes a little less, but that's typical. Multiplied by eight, that's a total of 18.4" - 19.2" of shells. With a space-efficient extension, spring, and follower, that can certainly fit under a 20" barrel. Slightly shorter shells really help when there's that many of them, too. With 2.27" - crimped shells rather than 2.3", the shells only take up 18.16" of the tube.

I haven't played with Mossbergs much, but it's my understanding that they're only 8+1 with certain 2.75" shells as well. And you mentioned that your 590's mag spring isn't terribly stiff. I think Mossbergs use a different mechanical setup for feeding shells, so maybe they're more tolerant of weak mag springs than 870s. Or, maybe they can have the same issues 870s have when the mag spring is too weak, but few users run them hard or fast enough to see those issues. There could also be some dimensional differences between the two guns, like the first shell in the magazine sitting further back relative to the breechface in the Mossberg than in the 870, thus buying a bit more space.

In any case, the 870 can definitely do 7+1 under an 18/18.5" barrel, and 8+1 under a 20" barrel. I've assembled both setups before. Again, if you want maximum capacity, you need to select the right magazine components. Not all kits for the 870 prioritize capacity, for various reasons. And sometimes, depending on various things including how the gun is used, you're better off with a more robust or reliable magazine setup that comes at the cost of one less round in the tube.

[Toamaius]

I put a +2 on my 18" 870 for a magazine capacity of 6. My 20" 590 has a magazine capacity of 8. This is a bit frustrating and I guess comes down to the spring. I really feel like I should be able to get 7 2.75" shells in there. The 7th shell comes very close to fitting and I'm thinking of grabbing a box of 2" Aguilas to test and if they run reliably, use as a topper-offer.

Anyone play around with these short shells in an 870?

Minishells aren't worth it. First of all, mini's sacrifice standard payloads found in their 2 3/4 inch counterparts.

I will use a typical #2 buckshot load. War Wolf Ordnance loads their roll crimped 2 3/4 inch #2 buckshot with 20 pellets. They also make a custom roll crimped mini shell which is loaded exactly the same from the was down, the only difference is it is a 10 pellet load.

My gun is a Vang Comp Systems 870 Tactical, 7 shot model with a solid magazine tube(one piece model 2013 and newer I believe) the point is it accepts six 2 3/4 inch or five 3 inch shells.

So, I can fit 8 War Wolf Ordnance mini shells. 8×10=80 pellets from a magtube from the 8 shots.

Now, I can fit 6 War Wolf Ordnance 2 3/4 inch shells. 6×20=120 pellets.

Also, it might take 2 shots from a mini shell to make an attacker stop, where it might only take 1 shot from a standard 2 3/4 inch shell.

I rather take twice the payload and give up 2 rounds in the magtube.


Now, more important than payload and shot count is reliability.... Like Synchronizor said in previous posts.

Mini shells tend to not be reliable from most shotguns including 870. I have had shells come out the magtube and lodge themselves in the chamber and wedged by the lifter. Worst yet, shell can do a 90 degree flip and, become wedged I a malfunctioning that requires some serious hands on to clear.

Remember, "Anything that can go wrong, will go wrong" especially when your life or someone you care about might be on the line....

I will take some pictures and possibly do a video on this malfunctioning.

Resounding NO on mini shells for anything but recreational or maybe an extra shell that comes out last in a magtube(load it first in magtube followed by 2 3/4 inch shells)