Firearms & Knives

Shotgun Magazine Capacities

So, why does you shotgun's tubular magazine only hold 6 shells when the manufacturer says it should hold 7?  Well, first off, make sure you really know the magazine capacity -- not the gun's capacity.  A Remington 7 shot shotgun is likely a "6 + 1" gun, 6 in the magazine and 1 in the chamber.

If you're sure you know the magazine capacity and you don't reach it, the magazine might not have the original factory spring or follower.

More likely, you are using shells with end-discs, not with crimped ends.  The length of a shell, such as 2 3/4" or 3", is the overall length of the shell after it is fired.  When a crimped shell is fired the whole crimp unfolds and adds to the length of the fired shell.  This means the unfired length  of a 2 3/4" shell must be 2 3/4" minus the crimp length.

A shell with an end disc only has a little bit of the shell turned over to hold the disc, which means the length of an unfired 2 3/4" shell can be much closer to 2 3/4".  (To digress for a second, these longer shells can cause feeding problems in some guns.)

These shells will stack up to the lengths shown in this table:
Stackup Lengths of 2 3/4" Shotgun Shells
Number of Shells 2.25" Shells
2.5" Shells

Note the 2" difference at 8 shells -- it can really add up.

To use this table, first measure the exact inside length of the magazine tube.  If it reaches out to the very tip of the barrel, the magazine length is likely the same as the barrel length.  Otherwise you'll have to measure it.

If you have a follower with a "tail" on it that the spring fits over and stops you from overcompressing it -- you're a wise man.  If you are using the correct spring for it and you are sure the compressed spring will fit over the tail, just measure the overall follower length and go to the next step.  Otherwise, fully compress the magazine spring by sliding it over a dowel and compressing it.  Measure this length.  (If you aren't brave enough to do this, use a micrometer to measure the wire diameter of the spring and multiply this buy the number of turns in the spring.)  Then measure the follower to see how much space it takes up in the magazine between the spring and the first shell.

Subtract the length of the compressed spring and the follower from the magazine length -- that's how much room you have left for shells if you want to compress the spring all the way.  Use the above table to see how many shells will fit.

And then -- my advice -- if there isn't at least an inch more to spare, put in one less shell.  There is no point in stressing the spring so it won't feed that last shell anyway.

Let's try an example -- gee I don't know.... how about the SPAS-12?  Mine with the full length extension measures 21.5" long.    The factory spring and follower are about 2" long.  21.5 - 2 = 19.5" left for shells.  This is room enough for 8 crimped shells, but only 7 disc-end shells.

What do I do with my SPAS-12?  Well, I happen to love these #0 buck tracer shells I have.  These have disc ends, so only 7 are going to fit.  Since I've got some space to spare, I put in a longer spring designed for 10 round magazines.  This always gets that last shell to feed.  I''ve seen the stock SPAS-12 spring fail to feed the last round on many occasions, once it gets old and it sits loaded for a few months.

Sometimes it  almost feels like you could squeeze just one more in, doesn't it? Don't!  Trying to force too many shells into any magazine can permanently damage the magazine spring.  As a matter of fact, unless it is a magazine that you know has huge safety margins in its design (like a Beretta 92) I would load it to capacity less one.  This makes the spring happier -- and if the spring isn't happy, it won't feed that last round, so what is the point of carrying it around?

Brownel's has a nice universal follower for shotguns that has a pin that you cut to length for your model that stops overloading and the damage it may cause.

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