One of the great things about owning the Smith & Wesson M&P Compact is that it will accept both the compact magazines, and the larger, higher capacity  magazines from the full size version of the M&P.  I own the M&P 9c (9mm Compact) which will accept both the 12 round compact magazine, and the 17 round full-size 9mm magazine.   When I carry my M&P 9c, I use the 12 round magazines (with finger extension) but at home or when I shoot for competition, I often use 17 round magazines. The problem with doing so however is that the lower portion of the 17 round magazines extend well beyond the end of the M&P 9c magazine well as illustrated in the below photo:

There are some 3rd party manufacturers who have created adapters to alleviate this problem – in fact, depending on which version of the M&P Compact is purchased, it may have come with one such adapter – the XGRIP:

FDI manufacturers their XGRIPS products for several different firearms including Smith & Wesson.  Essentially the XGRIP is a rubber sleeve which fits over the M&P magazine (the same adapter works for either the 9mm or .40 caliber M&P full size magazine):

As you can see, the XGRIP has a nice texture which not only helps provide a better no-slip grip on the gun, it emulates the texture pattern on the M&P to give it a more integrated look when installed:

The only problem with the XGRIP is that it tends to slide around a bit on the magazine if the magazine isn’t seated in the gun.  If you pick up a magazine by grabbing on to the XGRIP, you can easily drop the magazine as it can slide right out of the XGRIP adapter – problematic in a competition, and disastrous in a defensive situation.  In fact, I’ve heard more than one defensive training instructor advocate not using an adapter at all for this reason.  To remedy this issue, I simply apply some Gorilla Glue to the interior of the adapter which adheres the adapter to the magazine.  I’ve been using a couple of 17 round magazines with the XGRIP glued on in both competition and training courses I’ve taken in the past couple of years, and have never had a problem.  This solution however is not ideal if you have both a full-size M&P, and a compact version with which you want to share 17 round magazines – once the adapter is glued on, you can’t put the magazine in a full size M&P.

There is another manufacturer who makes a similar magazine adapter product for the M&P called the A&G Grip Extender:

The A&G Grip Extender differs in several ways from the XGRIP adapter.  The A&G Grip Extender is not rubber, but rater made from a hard plastic/FRN (fiberglass reinforced nylon) material, and has a small screw built into the adapter which is used to tighten down the adapter once on the magazine so it doesn’t slip off:

It even comes with the appropriate size hex wrench to tighten or loosen the screw in the back of the adapter.  The screw is an ingenious idea, and this particular adapter is in theory the ideal for M&P owners who have both the full-size and compact versions, and want to share magazines between the two.  In practice however, I’m not very fond of the A&G Grip Extenders.  They have a very smooth, slick exterior and don’t provide nearly the level grip which the XGRIP adapter provides – neither does their appearance integrate well with the the M&P:

Comparing two magazines which each have one of the two competing magazine adapters installed, the XGRIP adapter seems to have a better, tighter fit with the magazine than does the A&G Grip Extender:

Note the fitting gap in the A&G Grip Extender (right) as compared to the XGRIP adapter (left).

There is also a cost difference between these two adapters – XGRIP for the M&P 9mm/.40 retail for $19.95 (but can be found for less on Amazon by clicking here).  I’m actually not certain as to the retail price for the A&G Grip Extender for the M&P 9mm/.40 (click here to see the best price available on Amazon) but it does appear to sell for a bit cheaper than XGRIP do, which surprised me as it seems to be a more complex device than the XGRIP adapter.

I’m a proponent of using a magazine adapter for M&P full-size magazines with the M&P Compact pistols.  It’s certainly not a necessity – a full-size magazine will function perfectly well with an M&P Compact without the expensive of adding an adapter, or potential for the adapter somehow interfering with proper manipulation of the magazine.  I’d love to see A&G add some better texture and improve the fit of their Grip Extender for the M&P.  Even though XGRIP for the M&P are generally more expensive, I prefer their look, feel, and fit on the magazine.  This is one of those classic cases where I wish I could pick and choose the features/benefits of two competing products into one great product – the material texture of the XGRIP and the screw adjustment of the A&G Grip Extender.