Like the 10-22 the Mossberg 500 series of shotguns is extremely popular. Also like the 10-22 changing the stock is the easiest modification.
My 590 originally came with synthetic stocks, but I wanted to have a pistol grip along with the shoulder stock. I have always felt that tactical shotguns should have a pistol grip as it allows more control and helps reduce the felt recoil.
Looking a the different stocks available, they run from inexpensive and poorly designed to very innovative.
You could go with a Hogue overmolded stock. They fit like the OEM stocks but utilize the famous Hogue material which is tacky, this helps you keep a good purchase on your weapon:
They have them in zombie green as well as orange for LEO "less than lethal" rounds
Magpul recently began offering their unique MOE & SGA stocks & forends for Remington & Mossberg shotguns. They offer them in black, flat dark earth & orange (again for the LEO folks). Magpuls quality is superb as is their customer service.
another option is a Speedfeed stock, they have recesses in the buttstock that house 2 extra rounds on each side (4 total). They offer their stock with or without the pistol grip. Like Hogue & Magpul they offer these in orange for the law enforcement crowd.
(take a look at their website here)
Another option is the "Bullpup" design. I am usually wary of aftermarket bullpup kits. Mossberg actually offered this for a time as a factory option, from what I have read they function just as well as a standard stock/forearm set-up
This is the stock I originally purchased for my Mossberg, it is made by Black Warrior (now John Masen).
I liked it, but the angle seemed off and I would like to have a folder or collapsible stock to make the gun easier to transport.
ATI makes a couple of options:
Tapco offers their Intrafuse stock for the Mossberg
Choate wouldn't deprive Mossberg owners of their not-so aesthetically pleasing stocks
I have always liked the Fab Defense/MAKO Group's products, they have some really nice looking stocks and well thought out designs
Butler Creek makes a folding pistol grip stock using their stout, steel folding frame
Phoenix Technologies also offers two M-4 style butt stocks with an integral pistol grip
Blackhawk offers a couple of options that feature their recoil reducing technology
I chose to put this one last as it was my favorite stock system and it was also the system I purchased.
Mesa Tactical had an idea: make an adapter that would allow the shotgun owner to chose their butt stock and grip from the M-4/AR-15 offerings. I am not sure if they were the first to come up with the idea, but the other adapters I have seen were plastic and cheaply made. The Mesa Tactical ones are made of investment cast aircraft aluminum and they are made in the USA! This model is also available in a recoil reducing version, see it here.
Their kit comes with a Hogue AR pistol grip and a standard AR 4 position collapsible butt stock.
however, you can install any butt stock and grip that will fit an AR platform rifle, here is one using Magpul furniture.
The parts arrived loose in a plastic bag:
Here are the parts laid out, installation is a snap, they provide good instructions and the tools you need to get the job done
First step is to install the adapter using the cap screw and allen wrench. The parts fit nicely.
I then installed the buffer tube (sans buffer and spring). Be sure to put the lock ring and spanner nut on before threading it into the adapter. I forgot to snap a picture of that, but here it is on an AR rifle:
the installation is the same, the lock ring threads onto the buffer tube with the notches facing rearward, the index ring goes on next, it slides on by lining up a tab on the ring with a slot on the bottom of the buffer tube, this keeps it from spinning. Then thread the buffer tube into the adapter with a minimum of 3-4 threads, once you have it in deep enough and the stock straight up & down, slide the indexing ring forward into the slots on the adapter. Next tighten the lock ring by hand, then cinch it down with the provided spanner wrench.
Next I installed the Hogue grip with the screw provided.
Once I had everything tight, I could adjust my length of pull and install the QD sling attachment.
You can see in the pics, the adapter looks right at home.
The last item I added was a Limbsaver recoil pad. They make one that snaps on most AR butt stocks.
It was a little tough to get on, I had to use a small screw driver to pull the rubber around the butt plate, but once on, it fits like a glove. This will add an inch or so to the LOP.
If you have never tried Limbsaver products you are missing out. In my opinion, they have the best recoil absorbing material out there, and their products are made here in the USA.
Check them out here